The list below includes names taken from early Brythonic sources and those still used in Wales, Brittany and Cornwall today.

All forms have been standardised according to modern Welsh orthography, except modern Breton and Cornish forms, which are marked (B) and (C). Old Breton and Cornish forms with no modern equivalent have been given in standard modern Welsh and are marked with an asterisk (*).

Early sources used:

  • BGG: Bonedd Gwŷr y Gogledd, MS 13th C., possibly from 12th C. source
  • BM: Bodmin Manumissions, 9th – 10th C.
  • BS: Bonedd y Saint, MS 13th C.
  • HG: Harleian Genealogies, MS c12th C., possibly from 10th C. material
  • JC: Jesus College Genealogies, MS late 14th C.
  • T: Welsh Triads, late 13th C.
  • YG: Y Gododdin, late 13th C. possibly from much earlier material.
AeddanMW. Ædan, Aedan, OC. Aedan, E. Aidan. A borrowing from OI. Aedán (I. Aodhán), meaning ‘little fire’. HG, BM, BGG, YG
Angharad(f.) Br. *Ancaratā ‘well loved’ (W. caraf ‘I love’).
AnarawdMW. Anarant (sic.). Probably from L. Honōrātus meaning ‘distinguished’. HG
Anaostl* (C)(f.) OC. Anaguistl.  Probably ‘wealth hostage’ with W. anaw ‘wealth; wealthy’ and gwystl ‘hostage’. BM
AneirinMW. Aneurin, Aneirin. Of uncertain origin. Perhaps from L. Nigrīnus < niger ‘black’, or Br. *Nagrīnos, a derivative of PC. *nagro- (OI. nár ‘noble, honourable; modest’, náire ‘shame, bashfulness, modesty, decorum’). YG
AnthunE. Anthony. From L. Antōnius. HG
Arc’hantael (B)(f.). B. arc’hant ‘silver’ and ael ‘eyebrow’.
Artan, ArthanMW. Artan. Probably a borrowing from OI. Artán ‘little bear’, but it may be the Welsh cognate *Arthan. HG
Arthek (C)Br. *Artācos ‘bear-like’ (W. arth ‘bear’).
ArthfoddwMW. Artbodgu. Br. *Artobodwos ‘bear crow’ (W. arth ‘bear’, OI. bodb, badb ‘hooded crow’). HG
ArthialMW. ArtHGal, I. Árdal. From PC. *Artogalos ‘bear power’ (W. arth ‘bear’, gallaf ‘I am able’). HG
ArthienMW. ArtHGen.  From Br. *Artogenos ‘bear-born’ (W. arth ‘bear’).  HG
ArthurB. Arzhur. Probably the most famous Brythonic name, but of uncertain origin. Probably from L. Artōrius. HG, T, YG
Asa, AsaphMW. Assa. Probably the Biblical names Asa or Asaph. BS
Awen(f.) The common noun W. awen ‘inspiration, muse’, perhaps related to awel ‘breeze’.
BaglanMW. Baglan. W. baglan ‘crook, crutch’ from bagl ‘crosier, crook’. BS
BedwyrE. Bedivere. Probably Br. *Betwowiros ‘birch man’ (W. bedwen ‘birch tree’, gŵr ‘man’). t
BeliMW. Beli, OC. Beli. Of uncertain origin, though a relatively common name in the king lists. Perhaps from Br. *Bolgjos, *Belgjos < PC. bolg- ‘belly’ (W. bola), or a name relating to the god Belenos. HG, BM, YG, T, BS
BerwynMW. Berwin. Br. *Barrowindos ‘white top’ (W. bar ‘summit, top, crest’, gwyn ‘white’). JC
Bizouarn (B)OB. Budhoiarn. From B. buz ‘profit’ (previously ‘victory’) and houarn ‘iron’.
BleiddfanMW. Bleidvan.  Br. *Bledjomandus ‘wolf pony’ (W. blaidd ‘wolf’). YG
Bleiddgwn*OC. Bleidcum (sic.). Br. *Bledjocunam (acc.) ‘wolf hound’ (C. bleydh ‘wolf’, ki ‘dog’). BM
BleiddigFrom W. blaidd ‘wolf’ and the diminutive -ig. YG
BleidduddMW. Bleydiud, Bleiddut, OC. Bleidiud. From Br. *Bledjojüd- ‘wolf lord’ (W. blaidd ‘wolf’, udd ‘lord’). HG, BM, BS
BodgadMW. Botgat. Br. *Bodwocatus ‘battle crow’ (OI. bodb, badb ‘hooded crow’, W. cad ‘battle’).YG
BoddwMW. Bodgu. Br. *bodwo- ‘crow’ (OI. bodb, badb ‘hooded crow’). HG, YG
BradwenMW. Bratwen. Seemingly a compound of W. brad ‘treachery, treason’ and gwen ‘white’. YG
BrânMW. Bran. Br. *Branos ‘crow, raven’ (W. brân ‘crow’, OI. bran ‘raven’), a bird commonly associated with battles. HG, t
Branek (C)From Br. *Branācos ‘raven-like’ (C. bran ‘crow’)
BreichiolMW. Brechiaul. Possibly L. Bracchiālis < bracchium ‘arm’ (W. braich ‘arm, branch’), perhaps inferring ‘having strong arms’. There is a Welsh word breichiol ‘linked together; brachial’. HG, YG
Brengi*OC. Brenci. Probably Br. *Branocī ‘raven hound’ (C. bran ‘crow’, ki ‘dog’). BM
BriogOC. Frioc, C. Bryok, B. Brieg. Br. *Brīgācos ‘powerful, esteemed’ (C. bri ‘distinction, esteem, importance’). BM
BrochfaelMW. Brochmail, Brocmayl. Br. *Broccomaglos ‘badger prince’ (W. broch ‘badger’, mael ‘prince, lord’). HG
Bronwen(f.) Br. *Brondowindā ‘white breast’ (W. bron ‘breast’, gwen ‘white’).
Brezelgar* (B)OB. Preselgar. The first element is B. brezel ‘war’ and the second may be B. kar ‘friend’.
Brezelgevgant* (B)OB. Breselcoucant. B. brezel ‘war’ and the equivalent of W. ceugant ‘certain; special’.
Brezelgonan* (B)OB. Breselconan. B. brezel ‘war’ and the personal name Br. *Cunagnos (see Cynan).
Brezelvarc’heg* (B)OB. Breselmarcoc. ‘War horseman’ from a compound of B. brezel ‘war’ and marc’heg ‘knight’.
Brezelek* (B)OB. Breseloc. ‘Warlike’ from Br. *Bristelācos (B. brezelek ‘bellicose’).
Brythael*OC. Brithael. Perhaps Br. *Britosagelos ‘generous of judgment’ (C. bres ‘mind, thought’, hel ‘generous’). BM
BuanMW. Buan. Probably the common adjective W. buan ‘swift, nimble’. BS
BuddfanMW. Budvan. Br. *Büdomandus ‘victory pony’ (W. budd ‘profit, gain, riches’). YG
BuddugOC. Budic, OB. Budoc, B. Beuzec E. Boudica. From Br. *Büdīcos, Büdīcā ‘victorious’ (C. budhek ‘victorious’, W. buddig ‘victorious, successful, generous’). The Breton forms are from equivalent Br. *Büdācos. A female name in Welsh, but apparently masculine in Old Cornish and Old Breton. BM
Buzaret (B)OB. Buduuoret. B. buz ‘profit’ (previously ‘victory’) and gwared ‘protection’.
Buzval (B)OB. Butgual. The first element is B. buz ‘profit’ (previously ‘victory’) and the second may be Br. *walo- ‘leader’ (see Cadwal).
Cadan (C)Probably a diminutive of names in Cad-.
CadellMW. Catell, Catel, Kadell. Probably from L. catellus ‘puppy’ (see Cenau). HG, BS
CadfanMW. Catman, Katuan. Br. *Catumandus ‘battle pony’.  HG, T, BS
CadfannanMW. Catvannan. A dimunitive of Cadfan. YG
CadfawrMW. Catmor. Br. *Catumāros ‘great battle’ (W. cad ‘battle’, mawr ‘great’). MW. Catmor may be for Br. *Catumori ‘battle-sea’ or ‘sea battle’ (W. môr ‘sea’). HG
CadlewMW. Catleu. The elements may be W. cad ‘battle’ and glew ‘warrior, hero’; less probably llew ‘lion’. HG, YG
CadogOB. Cadoc, B. Kadeg. From Br. *Catācos ‘battle-like’ (W. cad ‘battle’). HG
CadoganMW. Catgocaun, W. Cadwgan. Properly *Cadogawn or *Cadogon from Br. *Catuwocānos ‘battle glory’ (W. cad ‘battle’, gogawn ‘glory, honour; satisfaction’).  HG
CadwalMW. Catgual, G. Cathal. Br. *Catuwalos ‘battle leader’ (W. cad ‘battle’).  HG
CadwaladrMW. Gatgualart (sic.), Katwalaudyr, OB. Catuualart (sic.). Br. *Catuwalatros ‘battle-leader’ (W. cad ‘battle’). HG, T, BS
CadwallonMW. Catgollaun, Catguallaun, Katwallaun, OB. Catuuallon. Br. *Catuwallānos ‘battle leader’ (W. cad ‘battle’).  HG, T, BS
CadwrMW. Catgur, OB. Catuur.  Br. *Catuwiros ‘warrior, battle hero’ (W. cad ‘battle’, gŵr ‘man’). HG
Cadwystl*(f.) OC. Catguistl.  Br. *Catugēstlā ‘battle hostage’ (C. kas ‘battle’, gostel ‘hostage’). BM
CaeogMW. Kayawc. From W. cae ‘hedge, fence, enclosure’, perhaps meaning ‘protector’. YG
CaradogMW. Caratauc, E. Caratacus, Caractacus. Br. *Caratācos ‘loving’ or ‘beloved’ (W. caraf ‘I love’). The modern Welsh ought to be *Cardog. HG, T, YG
CarannogMW. Carannauc. Br. *Carantācos ‘dear, beloved’ (W. carannog). BS
CateyrnMW. Cattegirn. Br. *Catutigernos ‘battle king’ (W. cad ‘battle’, teyrn ‘king’). HG
CawrdafMW. Caurtam, Caurdaf. Br. *Cawrotamos ‘most giant’ (W. cawr ‘giant’). HG, BGG, t
CedigMW. Kedic. Br. *Catīcos ‘battle-like’ (W. cad ‘battle’). BGG, BS
CeidioMW. Keidyaw, OB. Cadiou. A hypocoristic of names in Cad-. BGG, YG, t
CenauMW. Ceneu, Keneu. From the common noun W. cenau ‘whelp, puppy’ < Br. *canawū. HG, BGG, YG
CeredigMW. Ceretic, Keredic. Identical with Caradog, but with a different ending: Br. *Caratīcos ‘loving’ or ‘loved’. HG, YG, BS
CianMW. Gian. Either borrowed from I. Cían meaning ‘ancient, enduring’ or a late (post-Brythonic) diminutive of W. ci ‘dog’. YG
CilyddMW. Kilyd. From the W. common noun cilydd ‘fellow, companion’. YG
ClodriMW. Clotri. Br. *Clutorīgam (acc.) ‘famous king’ (W. clod ‘praise, fame, renown; famous’, rhi ‘king’). HG
ClydnoMW. Clydno. From Br. *Clutognāwjos ‘knowing fame’ (W. clod ‘praise, fame, renown’). BGG, YG, BS
ClydogMW. Clitauc, Clytauc, C. Klesek. From Br. *Clutācos ‘famous; famed one’ (W. clod ‘praise, fame, renown’). HG, JC
ClydwynMW. Clytwin. Br. *Clutowindos ‘blessed fame’ (W. (W. clod ‘praise, fame, renown’, gwyn ‘white, blessed’). JC
ClynogMW. Clinog, Clinoch. The origins of this name are uncertain. W. clynnog occurs as a syncopated form of celynnog ‘(place) abounding with holly’ in the place name Clynnog Fawr (Caernarfonshire). It is possible the personal name is the same word with the sense ‘holy-like’, in the vein of other names derived from trees. However, the records of this name are rather early for such syncope to have taken place and we might expect double -nn- to appear in the Middle Welsh spelling. There are no other clear candidates for the first element of the name. It is possible that this is merely a scribal error: the name only occurs in the Harleian Genealogy and the equivalent people are called Clydno and Kedic in the Bonedd Gwŷr y Gogledd.  HG
CoelMW. Coil, Coyl, Gyl, Coel. From the common noun W. coel ‘belief; omen; reputation’ < PC. *kailā (OI. cél ‘omen, portent’). HG, BGG
CorunMW. Corun. From L. corōna ‘crown, wreath’ (W. coron ‘crown’, corun ‘crown (of head), tonsure’). BS
CuneddaMW. Cuneda, Kuneda. A well-known name, probably from Br. *Cunodagos ‘good hound’ (W. ci ‘dog’, da ‘good’). The modern Welsh form ought to be *Cyndda, but it has retained a much older spelling due to it being passed down through written records. HG, BS
CyfwlchMW. Chyvwlch. The same as the adjective W. cyfwlch ‘complete, perfect, excellent’. YG
CynanMW. Cinan, Chynan. Br. *Cunagnos ‘little hound’ (W. ci ‘dog’, -an diminutive suffix). HG, BGG, YG
CyndeyrnMW. Kyndeyrn, E. Kentigern. Br. *Cunotigernos ‘hound king’ (W. ci ‘dog’, teyrn ‘king’). This cannot be from Br. *Cintutigernos ‘first king’, as is often stated, since this would produce W. *Cynteyrn. T, BS
CynfanMW. Chynvan. Br. *Cunomandus ‘hound pony’ (W. ci ‘dog’). YG
CynfarchMW. Cinmarc, Kynuarch. Br. Cunomarcos ‘hound horse’ (W. ci ‘dog’, march ‘horse’). HG, BGG, t
CynfelynMW. Cinbelim, Cinbelin, Chynuelyn, Kynuelyn. Br. *Cunobelinos ‘hound of the god Belenos’. HG, BGG, T, BS, YG
Cynfynog*OC. Conmonoc.  Br. *Cunomonācos ‘noble hound’ (C. ki ‘dog’, W. mynog ‘noble’). BM
CyngarMW. Cincar, Kyngar, C. Kengar. Probably Br. *Cunocaros ‘hound love’ (W. ci ‘dog’, caraf ‘I love’). HG, BS
CyngenMW. Cincen. Probably Br. *Cunocennos ‘hound skin’ (W. ci ‘dog’, cen ‘skin’). HG
CyninMW. Cinnin. Br. *Cunignos ‘little hound’ (W. ci ‘dog’). HG
CynlasMW. Cinglas. Br. *Cunoglassos ‘grey hound’ (W. ci ‘dog’, glas ‘blue, green, grey’). HG
CynriMW. Kynri. Br. *Cunorīgam (acc.) ‘hound king’ (W. ci ‘dog’, rhi ‘king’). YG
CynwalMW. Gynwal. Br. *Cunowalos ‘hound leader’. YG
Cynwr*OC. Cingur. Br. *Cunowiros ‘hound man’ (C. ki ‘dog’, gour ‘husband’). BM
CynwydMW. Cinuit, Kynnuyt. Identical in origin to the river name Kent from Br. *Cunētjū, perhaps meaning ‘health-giving’. HG, BGG, t
CynyrMW. Gynyr. From the nominative of the same name which gives Cynri, Br. *Cunorīx ‘hound king’ (W. ci ‘dog’, rhi ‘king’). BS
DeigionMW. Decion. Probably from L. Deciānus < Decius. HG
DeiniolMW. Deinyoel, E. Daniel. From L. Daniēl. BS
DewiMW. Dewi. From L. Davīd. BS
Dinogad, DingadMW. Dinacat, Dingat, Dinogat. Br. *Dīnocatus ‘battle fort’ (W. din ‘fort’, cad ‘battle’). The modern Welsh ought to be *Dingad. HG, JC, YG, BS
DogfaelMW. Docuael. BS
DunodMW. Dunaut, Dunawd. L. Dōnātus. HG, BGG, T, BS
Dwywai(f.) MW. Dewei. Probably a derivative of Br. *dēwā ‘goddess’ (W. duw ‘god’). BS, YG
DyfnwalMW. Dumnagual, Dyuynwal, Dyvynwal, Dyfynwal, B. Dunvel? G. Dòmhnall, E. Donald, Dunmail. From Br. *Dumnowalos ‘world leader’ (W. dwfn ‘deep’, G. domhan ‘universe’). HG, BGG, YG, BS
DyfnwallonMW. Dumnguallaun.  Br. *Dumnowallānos ‘world learer’ (W. dwfn ‘deep’, G. domhan ‘universe’). HG
EdernMW. Edyrn, Ætern, Edern. From L. Æternus ‘eternal’. HG, BS
EdnyfedMW. Iutnimet, Idnyuet, Edynyuet. Br. *Jüdonemetos ‘noble lord’ or ‘lord of the sacred place’ (Gaul. nemeton ‘sacred grove’, OI. neimed ‘sanctuary; sacredness, status’. Properly *Idnyfed in modern Welsh. HG, BGG, BS
EigionMW. Eiciaun. Presumably from Br. *Oceānus < L. Ōceanus meaning ‘ocean’ (W. eigion ‘ocean’). HG
EiluddMW. Eliud, OC. Iliud. Br. *Elujüd- ‘many lords’ (MW. udd ‘lord’). HG, BM
EinionMW. Eniaun, Enniaun, Einyaun. Probably from L. Anniānus, Aniānus. The name is usually explained as being from W. einion, eingion ‘anvil’, which is possible, but the origins of that word are uncertain and the MW. -aun suggests Br. *-ān- for the name whilst C. anwan ‘anvil’ suggests Br. *-an- for the common noun. HG, BS
EithinynMW. Eithinyn. From W. eithin ‘gorse, furze, whin’. YG
Elen(f.) L. Helena < Gk.  Ελενη. HG
EleutherMW. Eleuther.  L. Eleutherius from eleutheria ‘liberty’. HG
Elfodd, ElfoddwMW. Elbodgu. Br. *Elubodwos ‘many crows’ (Gaul. bodua-, OI. bodb, badb ‘hooded crow’). HG
ElffinMW. Elfin, Elffin, Elphin, G. Ailpein, Pict. Alpin. A name of uncertain origin, though L. Alpīnus meaning ‘Alpine’ would fit the Welsh phonetics perfectly. HG, BGG, YG, BS
EliMW. Eli. Probably the Biblical name. YG
EneasMW. Eneas. Biblical. BS
ErtHGiMW. ErtHGi. From Br. *Artocī ‘bear hound’ (W. arth ‘bear’, ci ‘dog’). YG
EudafMW. Eudaf.  Br. *Awitamos ‘most friendly’. YG
FferfarchMW. Feruarch. Br. *Feromarcos, meaning either ‘wild horse’ or ‘valiant horse’ (see below). YG
FferogMW. Ferawc. Perhaps Br. *Ferācos ‘wild one’ from L. ferus ‘wild, fierce’ (W. lledffer ‘half-wild’), or from W. ffêr ‘strong, valiant, ferocious; hero’ < L. ferōx ‘warlike’. YG
GarfonionMW. Garbaniaun, Garmonyawn. Probably L. Germāniānus, a derivative of *Germanus. HG, BGG
GeraintMW. Gereint.  From L. Gerontius. YG, t
Gloywfedd*(f.) OC. Gloiumed. Seemingly ‘sparkling mead’ (W. gloyw ‘bright, shining, sparkling’, W. medd, C. medh ‘mead’). BM
Gloywgen*(f.) OC. Gloiucen. Probably meaning ‘shining skin’ (W. gloyw ‘bright, shining, sparkling’, C. kenn ‘skin’). BM
GodebogMW. Guotepauc, Godebawc. May be a byname rather than a forename, from Br. *Wotepācos ‘protective’ < PC. *wotekʷ- ‘hiding place, shelter’. HG, YG
Gogawn, GwgawnMW. Guocaun, Gwgawn. Br. *Wocānos ‘glory’ (W. gogawn ‘glory, honour; satisfaction’). HG, YG, t
GorthebyrMW. Guortepir. Br. *Worteporīx, perhaps meaning ‘protective king’ with the same root as PC. *wotekʷ- ‘hiding place, shelter’. HG
GruffuddMW. Gripiud, OC. Grifiud. Of uncertain origin and meaning. The second element is certainly Br. *jüd- ‘lord’. The first may be lL. griphus < grips ‘griffin’. HG, BM
GwaednerthMW. Waetnerth. Meaning ‘blood-strength’ (W. gwaed ‘blood’, nerth ‘strength’). YG
GwallogMW. Guallauc. Probably from Br. *Wellācos from wello- ‘better’ (W. gwell). HG, t
Gwen(f.) MW. Gwen. Br. *windā ‘white’ (W. gwen). YG
Gwendolen(f.) Properly *Gwenddolen from W. gwen ‘white’ and dolen ‘ring‘.
Gwener(f.) E. Venus. From L. Veneris, the genitive of L. Venus.
Gwenfraith*, Gwynfrith*(f.) OC. Guenbrith. Br. *Windobriktā ‘white-speckled’ (C. gwynn ‘white’, brith ‘streaked, striped’). BM
Gwengen*(f.) OC. Guencen. Br. *Windocennā ‘white skin’ (C. gwynn ‘white’, kenn ‘skin’). BM
Gwengenedl*(f.) OC. Guencenedl.  Br. *Windocenetlā ‘white family’ (C. gwynn ‘white’, kenedhel ‘nation’). The word ‘white’ is frequently used to mean ‘blessed’ in the Brythonic languages, so the name probably means something like ‘a family blessing’. BM
GwidionMW. Guidgen, Guitgen, Gwydyen. From Br. *Widugenjos ‘tree-born’ (W. gwŷdd ‘trees’). The modern name ought to be *Gwyddien but has retained a partly archaic spelling. HG, YG
Gwladus(f.) MW. Gwladus, E. Gladys. Taken literally, the name is an adjective formed from the common noun W. gwlad ‘country’, as if it were a female form of Patrick < L. patricius ‘patrician’. This doesn’t appear to be a satisfactory explanation for most authorities, however.
Gwrfoddw*OC. Gurbodu. Br. *Wirobodwos ‘man crow’ (C. gour ‘husband’, OI. bodb, badb ‘hooded crow’). BM
Gwrgant*OC. Gurcant. From Br. *Wirocantos ‘man circle’ or ‘man host’ (C. gour ‘husband’, W cant ‘outer circle, rim; hoop’ or W. cant ‘troop, host’, OI. cét ‘troops’). BM
Gwrgi, Gwrgwn*MW. Gurci, Gurgi, OC. Gurci, Gurcon. From Br. *Wirocī ‘man-hound’. OC. Gurcon is from the oblique stem of the same name (Br. *Wirocunam (acc.) > W. *Gwrgwn). The natural outcome of the nominative would be W. *GwrYG, *GwyrYG, so the elements must have been reanalysed after the Brythonic period in order to retain the meaning of the name. HG, BM, BGG
GwrhaearnMW. Gurhaiernu. Br. *Wiro-isarnos ‘iron man’ (W. gŵr ‘man’, haearn ‘iron’). HG
GwrienMW. Gwryen. Br. *Wirogenos ‘man-born’ (W. gŵr ‘man’). YG
Gwrwared*OC. Gurguaret. Seems to be Br. *Wiroworetos ‘saviour’ (C. gour ‘husband’, W. gwared ‘deliverance, salvation, help’, gwaredwr ‘saviour’). BM
GwrwstMW. Gurgust, Gorust, G. Fearghas. Two similar names have probably converged here: PC. *Worgustos ‘great force’ or ‘best choice’ gives the rare OI Forggus whilst PC. *Wirogustos ‘man-force’ or ‘man-choice’ gives OI. Fergus (G. Fearghas). W. Gwrwst may be from either. HG, BGG, BS
Gwrwystl*OC. Gurguistl. Br. *Wirogēstlos ‘man hostage’ (C. gour ‘husband’, gostel ‘hostage’). BM
GwyddgwnMW. Guitcun. Br. *Widucunam (acc.) ‘tree hound’ (W. gwŷdd ‘trees’, ci ‘dog’). HG
GwyddnoMW. ?Guipno (sic.), Guydno. Probably Br. *Widognāwos ‘knowing trees’ or ‘tree-born’ (W. gwŷdd ‘trees’) but Br. *Weidognāwos ‘knowing vision’ (W. gwybod ‘to know’, gŵydd ‘presence’) is possible. HG, BGG
GwylogMW. Guilauc. Perhaps meaning ‘watchful, vigilant’ from W. gŵyl ‘feast, holiday; watch, guard, vigil’. Alternatively from W. gŵyl ‘modest, tender, kind, generous, glad’ (G. fial ‘generous, benign’). HG
GwynMW. Gwynn. Br. *Windos ‘white’ (W. gwyn).
Gwyndeyrn*OC. Guentigirn. Presumably Br. *Windotegernos ‘white king’ (C. gwynn ‘white’, mYGhtern ‘king’, W. teyrn ‘king’). BM
Gwynllyw*MW. Guynlleu. Probably Br. *Windoluwī ‘fair or blessed ruler’ (W. gwyn ‘white’, llyw ‘ruler’). BS
Gwynwiw*(f.) OC. Guenguiu. Identical to the Middle Welsh adjective gwynwiw ‘white and fair’, from W. gwyn ‘white’ and gwiw ‘fitting, proper, fair, handsome, good’. BM
Hedrek (C)Br. *Sitrācos ‘strong or bold one’ (W. hydr ‘brave, bold, strong’).
HeiddynMW. Heidyn, OC. Hedyn. From Br. *sesjo- ‘barley’ (W. haidd) with the diminutive ending Br. *-innos (W. heiddyn ‘a grain of barley’). BM, YG
HoywgiMW. Hoewgir (sic.). Meaning ‘lively dog’ (W. hoyw ‘alert, agile, lively’, ci ‘dog’). YG
HyfaiddMW. Himeyt. Probably Br. *Sumedgos, *Subedgos ‘very daring’ (W. baidd ‘daring’). HG
HywelMW. Higuel, B. Hoël. From Br. *Suwelos ‘well seen’ in the sense of ‘respectable’ (W. gwelaf ‘I see’). HG
Iarnwallon*, Haearnwallon*OC. Iarnguallon. Br. *Isarnowallānos ‘iron leader’ (C. horn ‘iron’). BM
IagoW. Iago, C. Jago, E. Jacob, James. From L. Iacobus from Hebrew. BS
IdnerthMW. Iudnerth, OC. Iudnerth. Br. *Jüdonertos ‘lord of strength’ (MW. udd ‘lord’, W. nerth ‘strength’). HG
IdrisMW. Iudris. Uncertain. The first element is clearly Br. *jüd- ‘lord’ and the second may be Rhys (q.v.). The name may therefore mean ‘glorious lord’ or ‘heroic lord’. HG
IdwawlMW. Iutguaul. From Br. *Jüdowālos, probably ‘lord of light’ (W. gwawl ‘light, brightness, splendour’). W. gwawl also means ‘wall, rampart; boundary’, so the name may mean ‘march lord’. HG
IeuafMW. Iouab. A by-name meaning ‘junior’ from W. ieuaf ‘youngest’. HG
Ieuan, Ioan, Ifan, IwanMW. Yeuan, B. Yann, C. Jowan, E. John. From L. Iōhannes from Hebrew. YG
IeuenolMW. Iouanaul, E. Juvenal. From L. Iuvenālis meaning ‘youthful’.  HG
IlltudB. Iltud. Probably Br. *Elutütos ‘many people’ (B. tud ‘people, folk’).
IthaelMW. Ithael. From Br. *Jüdosagelos ‘generous lord’ (W. udd ‘lord’, hael ‘generous).
Jennifer (C)(f.) W. Gwenhwyfar, E. Guinevere. From Br. *Windosɛ̄barā ‘white spectre’ (C. gwynn ‘white’, OI. síabair ‘spectre, phantom’).
Kadlaouen* (B)OB. Catlouen. Probably ‘battle joy’ (B. kad ‘fighting, combat’, laouen ‘joy’).
Kadored (B)OB. Catuuoret. Meaning ‘battle protection’ from B. kad ‘fighting, combat’ and gwared ‘protection’.
Kadvuz (B)OB. Catbud. Br. *Catubüdos ‘battle victory’ (B. kad ‘fighting, combat’, buz ‘profit’).
Kanevet (B)OB. Catnimed. From Br. *Catunemetos, the first element is B. kad ‘fighting, combat’ and the second is neved ‘sanctuary’.
Katouarn (B)OB. Cathoiarn. ‘Battle iron’ from Br. *Catu-isarnos (B. kad ‘fighting, combat’, houarn ‘iron’).
Kenal (C)From Br. *Cunosagelos ‘generous hound’ (C. ki ‘dog’, hel ‘generous’).
Keneder (C)Br. *Cunositros ‘bold hound’ (C. ki ‘dog’, W. hydr ‘bold, brave, strong’).
Kenver (C)Br. *Cunomāros ‘great hound’ (C. ki ‘dog’, meur ‘great’).
Lleënog*MW. Leennauc. This would seem to be the same as W. llenog ‘priestly, literate, learned; scholar, cleric’, from W. llên ‘literature, learning; clerical’ < L. *legenda ‘to be read’. BS
Lleuddin*MW. Leudyn, Leudun. Probably from Br. Lugudīnos ‘fort of the God Lugus’ (W. Lleu ‘Lugus’, din ‘fort’). Lleuddin is the eponymous founder of Lothian or Lleuddiniawn ‘territory of Lleuddin’, so the name may actually be that of a place originally. The element din does occur in other personal names, however, and the suffix -iawn, -ion is attached to personal names as in W. Ceredigion ‘Cardigan’. BS
LlywarchMW. Llywarch, OC. Loumarch. Br. *Lugumarcos ‘horse of the god Lugus’ (W. Lleu ‘Lugus’, march ‘horse’). BM, BGG, YG, t
LlywelynFrom Br. *Lugubelinos, a combination of the divine names Lugus (W. Lleu) and Belenos.
LlywriMW. Llywri. Probably Br. *Lugurīgam (acc.) ‘king of the god Lugus’ (W. Lleu ‘Lugus’, rhi ‘king’), but perhaps the first element is W. llyw ‘rudder; ruler’.
Macsen, MaxenMW. Maxim, Maxen, C. Massen. From L. Maximus (in particular the Roman emperor Magnus Maximus, known as Macsen Wledig in Welsh). The name was evidently recorded at an early date according to its Latin origins and the modern Welsh name is a learned, phonetic rendering of the medieval written form. If the name had continued in use it would have become W. *Meisyf. HG, BGG, t
MadienMW. Madyen. Br. *Matugenos ‘bear-born’ (OI. math ‘bear’). YG
MadogMW. Madawc. From Br. *Matācos, either meaning ‘bear-like’ (OI. math ‘bear’) or ‘good’ (W. mad ‘good, virtuous, beneficial’). YG
Mael (B)Br. *Maglos ‘prince’ (W. mael ‘prince, chieftain, lord’).
MaelgwnMW. Mailcun, Maelgun. Br. *Maglocunam (acc.) ‘hound prince’ (W. mael ‘prince, chieftain, lord’, ci ‘dog’). HG, BS
MaelgwynBr. *Maglowindos ‘white prince’ or ‘blessed prince’ (W. gwyn ‘white; blessed’, mael ‘prince, chieftain, lord’). t
MaelogOC. Maeloc. Br. *Maglācos ‘princely’ (W. mael ‘prince’). BM
MarchOC. March. From the common noun meaning ‘horse’ (W. march, C. margh). BM, t
Marchell(f.) MW. Marchell. From L. Marcella < Marcus. JC
MarchlewMW. Marchlew. Br. *Marcolewū ‘horse lion’ (W. march ‘horse’, llew ‘lion’). The second element may be W. glew ‘bold; hero’. YG
MareduddMW. Margetiud, Morgetiud, E. Meredith. Of uncertain origin, the final element is Br. *jüd- ‘lord’. HG
MarroMW. Marro. Of uncertain origin, but perhaps a hypocoristic of a name in March-. YG
Mawn, MaunMW. Maun. Uncertain, but potentially related to the divine name Mogons meaning ‘great’, or to the epithets of St Patrick Magonus, Mauonius, Maun, which may be from the same source or from PC. *magu- ‘servant’ (C. mowes ‘girl’, MW. meudwy ‘hermit’). HG
Meddwystl*(f.) OC Medguistl. The second element is clearly C. gostel, W. gwystl ‘hostage’, but the first may be either C. medh, W. medd ‘mead’ or W. medd ‘power, authority’. BM
MeirchionMW. Merchianum, Meirchaun. From L. Marciānus, a derivative of Martius, Marcius. HG, BGG, t
MeirionMW. Meriaun, Meiryaun. From L. Mariānus, a derivative or Marius. HG, BS
MerfynMW. Mermin, OC. Mermin, E. Mervin, Mervyn, Marvin. A raft of explanations have been given for this name, none of which are particularly satisfactory. The only reliable source available to me gives the curious ’eminent marrow’ from W. mêr ‘marrow (literal and figurative)’ and *myn ’eminent’, the latter of which does not occur in the Geiriadur Prifysgol Cymru so is questionable. Other suggestions such as ‘sea friend’, ‘sea lover’ and ‘sea hill’ obviously take the first element to be W. môr ‘sea’ but have inexplicable second elements. Môr is the only reasonable candidate for the first element and it occurs in several other Brythonic names. The second element is less certain, but W. myn ‘desire, wish, will’ or myn ‘crown, diadem’ would both fit. HG, BM
MerinMW. Merin. Probably Br. *Morīnos ‘sea-like’ or *Morignos ‘little sea’ (W. môr ‘sea’). YG
MerwyddMW. Merguid. Br. *Moriwidus ‘sea tree’ (W. môr ‘sea’, gwŷdd ‘trees’). HG
MeurigMW. Mouric. L. Mauricius < Maurus ‘dark-skinned, Moorish’. HG
Modred (C)OC. Medrod, W. Medrawd, E. Mordred. Probably from Br. *Mātrātos or the like < *Mātr- ‘mother’. BM
MôrMW. Mor, OC. Mor. Simply ‘sea’ (W. môr ‘sea’). HG, BM
MordafMW. Mordaf. Perhaps Br. *Mārotamos meaning ‘the greatest’. BGG, t
MorfaelMW. Mormayl. Br. *Morimaglos ‘sea prince’ (W. môr ‘sea’, mael ‘prince, lord’). HG
MorganMW. Morcant, OC. Morcant. Br. *Moricantos ‘sea circle’ (W. môr ‘sea’, cant ‘outer circle, rim; hoop’) or ‘sea host’ (W. cant ‘troop, host’, OI. cét ‘troops’). HG, BM, t
MorialMW. Moryal. Br. *Morigalos ‘power of the sea’ (W. môr ‘sea’, gallaf ‘I am able’). YG
MorienMW. Morgen, Moryen.  Br. *Morigenos ‘sea-born’ (W. môr ‘sea’). HG, YG
MoruddMW. Moriud. Br. *Morijüd- ‘sea lord’ (W. môr ‘sea’, udd ‘lord’). HG
MynogMW. Mynawc.  Br. *Monācos ‘noble’ (W. mynog ‘noble, eminent; lord’). YG
MyrddinB. Merzin, E. Merlin. Br. *Moridīnon ‘sea fort’ (W. môr ‘sea’, din ‘fort’). The original name for Carmarthen (W. Caerfyrddin), but possibly also a personal name since both elements are known in other Brythonic names.  
NeithonMW. Neithon, Nwython, Pictish Nechtan, G. Neachdainn. Of unknown origin, but perhaps originally a divine name like Br. *Nektonos, related to L. Neptūnus ‘Neptune’. HG, YG
NuddMW. Nud. From the divine name Br. *Nüdens. BGG, T, BS
NyfedMW. Nyuet. From the common noun Br. *nemeton ‘sacred place’ or the adjective *nemetos ‘noble’. YG
OwainMW. Ywein, Ewein, Eugein, Ouen, Owein, B. Ewen, E. Owen, Ewan, G. Eòghann. Either from PC. *Esugenjos ‘born of the god Esus‘ or Gk. Ευγενιος (Eugenios) ‘well born’. HG, YG, T, BS
PadarnMW. Patern. From L. Paternus ‘paternal’. HG
PasgenMW. Pascent. Of uncertain origin, probably derived from L. Pascha ‘Easter’ (W. Pasg) or L. pāscō ‘I feed, foster, keep, cherish; graze’ (W. pasg ‘fattened, pasgaf ‘I feed, fatten, nourish’). The present participle L. pascentem (acc.) ‘feeding, nourishing, cultivating’ may be the direct origin of the name, perhaps with Christian overtones of spiritual nourishment.  HG
PedrMW. Petr, Pedyr, E. Peter. From L. Petrus < Gk.  Πέτρος (Petros) meaning ‘stone, rock’. HG, BS
PeithanMW. Peithan. From Br. *pekto- ‘strength’.
PeredurMW. Peretur, Pheredur, Peredur. no serious attempts seem to have been made to explain this name; it may contain the L. suffix –tōrius. HG, BGG, YG, t
Rhiainfellt(f.) A compound of W. rhiain ‘maiden’ (originally ‘queen’ from the same root as W. rhi ‘king’) and mellt ‘lightning’. 
Rhian(f.) An alteration of W. rhiain ‘maiden’.
Rhiannon(f.) From Br. *Rīgantonā ‘divine queen’ (W. rhiain ‘maiden’).
Rhiol*OC. Riol. Probably Br. *Rīgālos ‘kingly’ (C. riel ‘royal’, W. rhi ‘king’). BM
RhiwallonMW. Rhiwallawn.  Br. *Rīgowallānos ‘king leader’ (W. rhi ‘king’). t
RhodriMW. Rotri.  Perhaps Br. *Rātorīgam (acc.) ‘king of troops’ (W. rhawd ‘course; troop’, rhi ‘king’) or *Rotorīgam (acc.) ‘wheel king’ (W. rhod ‘wheel’). HG
RhufawnMW. Rumaun, Ruvawn. L. Rōmānus meaning ‘Roman’. HG, YG, t
RhunMW. Run.  Perhaps PC. *roino- ‘hill, plain’ (G. raon ‘plain, field’). HG, T, BS
RhydderchMW. Riderch, Ryderch. Often said to mean ‘very red’ or ‘reddish-brown’ in connection with OI. derg ‘red’ (G. dearg), but the root which gives OI. derg would yield *dery in Welsh. The origin is in Br. *Roderkos, connected with OI. derc ‘eye’, dercaim ‘I behold’, Gaul. derco- ‘eye’, so the name means ‘well-seen, remarkable’ or something similar. HG, BGG, t
RhysMW. Rys. Related to W. rhyswr ‘hero, champion, warrior’ and rhysfa ‘attack, assault, combat’. YG
Riwal (B)Br. Rīgowalos ‘king leader’ (B. ri ‘king’).
SawylMW. Samuil, Sawyl. From L. Samuēl from Hebrew. HG, BGG, BS
Seisyll, SeisylltMW. Seissil. From L. *Saxillus < Saxō ‘Saxon’. HG
SelyfMW. Selim, E. Solomon. From L. Salomō from Hebrew. HG
SerwanMW. Serguan, Seruan, E. Serf, Servan. From L. Servanus < servus ‘servant’.  HG, BGG, t
SerwilMW. Serguil.  L. Servīlius < Servius. HG
Siân(f.) E. Jane. Borrowed from OF. Jehanne via Middle English.
Tanghwystl, Tangwystl(f.) MW. Tancoystl, OC. Tanguistl Br. *Tancogēstlā ‘peace hostage’ (W. tanc ‘peace, truce’, gwystl ‘hostage’). HG, BM
TaliessinMW. Talyessin. Br. *Talojastīnos ‘radiant brow’ (W. tâl ‘end, forehead’, iesin ‘fair, beautiful; radiant, shimmering, bright’). YG, t
TegidMW. Tacit. From L. Tacitus ‘unsaid’. HG
TeilioMW. Teilyau. A hypocoristic (pet name) of *Eiludd with the pronoun ty ‘your’ prefixed. BS
TewdrigMW. Tewdric. A borrowing from OE. Þeodric.
TewdwrMW. Teudebur, W. Tewdwfr, E. Tudor, Theodore. An attempt to render L. Theodorus < Gk. Θεοδωρος using Welsh elements. The name would literally mean ‘fat water’. HG
TudfwlchMW. Tutuwlch. A compound of W. tud ‘people, tribe, nation, family’ and bwlch ‘cleft, mountain pass’, the symbolism of which is not entirely clear. BGG, YG
TudwalMW. Tudgual, Tutagual, Tutwal. Br. *Tütowalos ‘people leader’ (W. tud ‘people, tribe, nation, family’). HG, BGG, t
TwrchMW. Twrch. From the common noun W. twrch ‘boar’. YG
UnwstOC. Ungust, G. Aonghas, E. Angus. From PC. *Oinogustus ‘one force’. BM
UrienMW. Urbgen, Yrien, Uryen. Probably from Br. *Orbjogenos ‘heir born’ (OI. orbae ‘legacy, inheritance’ < PC. *orbjo-), which regularly yields MW. Yrien. The origin of the U- has been ascribed to rounding caused by the original –b-, or to a lengthening of the initial *O- > *Ō- > U-. Alternatively, U- may have begun as an attempt to write the rounded front vowel created by i-affection of o, with some scribes retaining this spelling even after the pronunciation had merged with Y-. HG, BGG, T, BS
Yannig (B)A diminutive of B. Yann ‘John’.
Yezekael (B)OC. Iudicael, E. Judicael. Probably Br. *Jüdicosagelos ‘generous lord’. The Br. stem *jüd- may derive from L. iūdex ‘judge’; if so, this name appears to preserve the original consonant stem of a Br. *jüdicam (acc.), whereas other names with *jüd- appear to show that it was reanalysed as a vowel stem such as *jüdos.  


  1. The Br. *jüd- may derive from L. iūdex ‘judge’ or it may be native PC. *joud-. As a common noun it appeared in Middle Welsh as udd ‘lord’ and it became a common element in personal names.