Sound Changes in Brythonic Languages

During the first millennium AD, the Celtic language of Great Britain (called Common Brittonic) underwent a series of sound changes which utterly changed the language and led to the establishment of Cumbric, Welsh, Cornish and Breton as separate daughter languages. Altogether these changes form a complex pattern – large volumes are filled with discussions of the various developments and some of the finer details remain a mystery. This page gives a general overview of some of the most important changes.

Timeline of Major Changes

Onset of lenition (by 1st C AD)

At some time in the prehistory of the Insular Celtic languages (Brittonic and Goidelic), people began to pronounce consonants standing between vowels more loosely compared with those after consonants or at the end of a word. The difference was one of strength, with consonants between vowels being weakened or lenited (from L. lenis ‘weak’), but it was also one of length as old double consonants fell together with their unlenited (or radical) equivalents. This change occurred not only within words but between them, so in PC *Sindos Wiros Māros ‘this big man’ the initial *W and *M kept their strong pronunciations (represented here by capital letters), but in *Sindā kattā mārā ‘this big cat’ the *k and *m are lenited.

This process goes back to a time when Brittonic and Goidelic were essentially one language and may even have occurred in Continental Celtic languages, but it produced different outcomes in the two branches of Insular Celtic (see Consonant Mutations). In Brittonic it eventually led to the following series of changes:

• p, t, c > b, d, g > v, ð, ɣ
• s, sw, st > h, hw, ss
• m > ṽ
• W, N, L, R > w, n, l, r

PC *j > Br. ð (4th-5th C)

Between a stressed e or i and another vowel, PC *j became late Br. *ð (W dd, C dh, B z), so PC *newijo- ‘new’ > W newydd, B nevez.

A-Affection (5th C)

When PC *i or *u stood before a word-final -a or -ā, they were lowered to *e, o (e.g. PC *windos, *windā ‘white’ > W gwyn, gwen, *butā ‘be’ > W bod).

Secondary Lenition/Spirantisation (5th C)

Following the completion of the first process of lenition almost every Brittonic consonant had both a strong and lenited variant (e.g. R ~ r; T ~ d; K ~ g; B ~ v etc.). This led to a secondary process of lenition, which reduced strong consonants to weak ones between vowels or following r, l. This produced the following changes:

• p, t, c > f, th, ch (between vowels and after r, l)
• b, d, g, m > v, ð, ɣ, ṽ (after r, l).

Final I-Affection (5th-6th C)

When a word had late Br. i, ī, ȳ or j in the final syllable, a preceding vowel might be heightened and fronted. The most common changes were a and o > ei, e or i; e,u > i (the affected forms of o, u may have retained their rounding for a time). These changes account, for example, for some WCB plurals such as W brain, B brin(i) ‘ravens’ < Br. *branī, W ŵyn ‘lambs’ < Br. *ognī.

Nasalisation (5th-6th C)

Where a combination of nasal (n, m) + voiced stop (b, d, g) come together, either within a word or between words, the two sounds merge: n + d = nn, n + g = ng, m/n + b > mm. For example, *windos ‘white’ > C gwynn; men’ damatos ‘my sheep’ > W fy nafad.

Loss of final syllables (5th-6th C)

Much like Latin, Brittonic had a strong inflection system which meant that most words ended in a syllable which gave information like gender, number and person. These syllables had probably been weakening over centuries alongside the other sound changes listed above and by the 6th century final syllables were lost entirely. This was the most significant change to the Brittonic languages, which utterly changed the way words sounded and the way grammar worked. Now the mutations such as lenition and nasalisation were fossilised (since the sounds that caused them were no longer there) and they became a way of compensating for the lost syllables. For example, the sentences given above, *Sindos Wiros Māros and *Sindā kattā mārā became W y gŵr mawr (masculine singular noun and adjective) and y gath fawr (feminine singular noun and adjective).

Loss of composition vowels (5th-6th C)

Brittonic compound words were joined together with a composition vowel – usually o – which was the original final syllable of the first element and these were lost, much as final syllables were. For example Br. *senotatos ‘grandfather’ > W hendad. In some early texts these composition vowels sometimes survive, especially in personal names, e.g. Urvaen ‘Urien’, Dinogad, Cunedda.

Consonants

PC	Brit.	Notes	W	C	B
b	b	initial intervocalic, lenited geminate	b f b	b v b	b v b
d	d	initial intervocalic, lenited geminate	d dd d	d dh d	d z d
g	g	initial intervocalic after r, l lenited geminate	g – y, a, i – g	g – gh – g	g – c’h c’h g
j	j	initial	i	y	y
k	c	initial intervocalic, lenited geminate kt	c g ch ith	k g gh ith	k g c’h izh
kʷ	p	initial intervocalic, lenited	p b	p b	p b
l	l	initial geminate elsewhere	ll ll l	l ll, l l	l ll, l l
m	m	initial intervocalic lenited geminate, mb	m f f m	m v v m, mm	m v ñv m, mm
n	n	geminate, nd nt ng nc	n n, nn n, nh ng ngh	n n, nn ns ng nk	n nn nt ng nk
φ	–	φt > kt	– ith	– ith	– izh
r	r	initial intervocalic geminate	rh r r, rr	r r rr	r r rr
s	s	initial sφ st	h ff s	h f s, st	h f s, st
t	t	initial intervocalic, lenited geminate	t d th	t d, s th	t d zh
w	w	initial intervocalic	gw w	gw w	gw w

Vowels

PC	Brit.	Notes	W	C	B
a	a	before -kt	a ae	a e	a e
e	e	before n/m in certain positions before -kt	e y ei, ai	e e	e ei, e
i	i	before -kt	y i	e i	e i
o	o	before n/m in certain positions before -kt	o w, y oe	o oy, o	o oa
u	u	in non-final syllables sometimes before -b, -m before -kt	w y u wy	o u oo	o, ou u oue
ā	ā	in monosyllables in final syllables in non-final syllables	aw o o	eu e o	eu e o, eu
ī	ī		i	i	i
ū	ȳ		i	i	i

Dipthongs

PC	Brit.	Notes	W	C	B
ai	ɛ̄		oe	oo	oa
ei	ē		wy	oo	oa, oe, oue
oi	ü		u	u	u