Wiktionary:About Proto-Brythonic

Proto-Brythonic is the last common ancestral stage of the Brythonic languages: Western Brythonic Welsh, Southwestern Brythonic Breton and Cornish, and likely Cumbric as well.

Phonology and notation

Consonants

• Sonorants: *l, *ll, *r, *rr, *m, *n
• Approximants: *j, *w
• Voiceless plosives: *p, *t, *k
• Voiced plosives: *b, *d, *g
• Labialized voiced plosives: *gw
• Voiceless fricatives: *f, *θ, *x, *h, *s
• Labialized voiceless fricatives: *hw
• Voiced fricatives: *β, *ð, *ɣ, *β̃

Vowels

• Back rounded: *u, *o, *ọ
• Central rounded: *ʉ
• Front rounded: *ü, *ö
• Central unrounded: *a, *ɨ
• Front unrounded: *e, *ė, *i

/oɨ/ and /uɨ/ were the regular development of long /ɛː/ and /eː/, respectively, while also resulting from vocalization of certain consonants following /o/ and /u/, whence also developed /aɨ/ and (partially) /ei/.

Diphthongs

I-dipthongs:

• Front unrounded: *ėi, *ei
• Front rounded: *üi, *öi
• Central unrounded: *aɨ
• Central rounded: *ʉɨ
• Back rounded: *uɨ, *oɨ, *ọɨ

U-diphthongs (which we spell with w):

• Front unrounded: *iw, *ɨw,*ėw, *ew
• Front rounded: *üw, *öw
• Central unrounded: *aw
• Central rounded: *ʉw
• Back rounded: *ow, *ọw

Developments from Proto-Celtic

Vowel development from Proto-Celtic to Late Brythonic:

Proto-Celtic	Proto-Brythonic
	Normally	a-aff.	final i-aff.	intern. i-aff.
u	u	o	ü	ü
o	o		ü	ö
i	ɨ	e
e	e		ɨ	ė
a	a		ė	ė
ū	i
ī	i
ā	ọ
au	ọ
ai	oɨ
ei/ē	uɨ
oi	ʉ
ou	ʉ

In closed pretonic and pre-pretonic syllables, short -u- and -i- had been been reduced to rounded and unrounded schwas, respectively.

Vowel affection

A-affection

When followed by the vowel /a/ in the final syllable, the short high vowels /i/ and /u/ are lowered to /e/ and /o/, respectively.

• Proto-Celtic *wlidā > Proto-Brythonic *gwleð

This leads to a masculine-feminine distinction in some o-stem adjectives, as the masculine form continues /i/, and the feminine form now has /e/.

• Masculine *gwɨnn vs feminine *gwenn

Final i-affection

When short back or non-high front vowels in penultimate position are followed by front high vowels or semivowels, mainly /iː/ or /j/, they are subsequently fronted and (if possible) raised:

• /e/ becomes /i/:

Short /e/ is also the only vowel that is affected by short /i/: Proto-Celtic *gʷeltis > Proto-Brythonic *gwɨlt

• /a/ becomes raised /e̝/: Proto-Celtic *rīganī (“queen”) > Proto-Brythonic *rriɣėn
• /o/ and /u/ become /y/: Proto-Celtic *ɸlowī > Proto-Brythonic *llüw

Internal i-affection

When short non-front-high vowels in any position are followed by front high vowels or semivowel /i/, /e̝/, /y/ or /j/, they are raised and/or fronted:

• /e/ and /a/ become /e̝/:
• /u/ becomes /y/:
• /o/ becomes /ø/:

Miscellaneous raisings

/e/ and /o/ raised to /i/ and /u/ respectively before -rn-. o also raised to u before -rg-. /e/ also raised to /i/ before intervocalic -g-. These raisings may be reversed if a-affection is present.

Consonant mutation

Initial consonant mutation is essentially the same phenomenon as lenition, as well as other forms of consonant development, only now applied across word-boundaries. *esyo tegos > *esyo degoh (lenited); *esyās tegos > *esyāh tegoh > *esyāh θegoh (spirantized).

In the table below, the symbol ◌̞ is used to indicate a more weakly articulated version of a consonant, and ◌̬ to indicate a partially voiced version of a voiceless consonant; in both cases which the lenited consonant is derived from this version.

Radical	Lenited	Spirantized	Nasalized
b	β (< b̞)	No change	m
d	ð (< d̞)		n
ɡ	ɣ (< ɡ˕)		ŋ
p	b (< p̬)	f	mh
t	d (< t̬)	θ	nh
k	ɡ (< k̬)	x	ŋh
m	β̃ (< m̞)	No change	No change
ll	l
rr	r
s	h (< s̞)
st	s(s)
ɡw	ɣw		ŋw

Development in the Brythonic languages

Basic vowel reflexes

Proto-Brythonic	Breton	Cornish	Welsh
ʉ	u	u	u
u		o	w, y
o	o	o	o
ọ	eu	eu, e	aw, o1, 2
a	a	a	a
e	e	e	e
ė	e, ei	y	e, ei, ai3, y
i	i	i, y	i
ɨ	e	i	y
ü		e	y
ö		e	e
uɨ	oue	o, oy	wy
oɨ	oe, oa, oua	oe, oy	oe
aɨ	ae	e	ae
ei	ei	ey, y	ai3, ei
ėi
üi	ei	ea	wy

Notes:

• ¹ In non-stressed Old Welsh syllables.
• ² Accent shift from ultima to penultima beyond Old Welsh caused monophthongization of ⟨aw⟩ to ⟨o⟩.
• ³ ⟨ei⟩ becomes ⟨ai⟩ in Modern Welsh stressed monosyllables and final syllables.

Miscellaneous changes

The sequence *wo- led to *wa- in leniting positions, but was retained in non-leniting positions. This allomorphy was resolved separately in the daughter languages, with one reflex being generalized over the other.

Nouns

The plural is usually formed based on the Proto-Celtic nominative plural.

o-stem (masculine)	Proto-Celtic	Proto-Brythonic	Welsh
Singular	*bardos	*barð	bardd
Plural	*bardoi	*bėrð	beirdd

o-stem (neuter)	Proto-Celtic	Proto-Brythonic	Welsh
Singular	*argantom	*arɣant	arian
Plural	*argantā	*arɣant	*arian1

yo-stem	Proto-Celtic	Proto-Brythonic	Welsh
Singular	[Term?]	[Term?]	[Term?]
Plural	[Term?]	[Term?]	[Term?]

ā-stem	Proto-Celtic	Proto-Brythonic	Welsh
Singular	*trebā	*treβ	tref
Plural	*trebās	*treβ	*tref1

yā-stem	Proto-Celtic	Proto-Brythonic	Welsh
Singular	[Term?]	[Term?]	[Term?]
Plural	[Term?]	[Term?]	[Term?]

ī/yā-stem	Proto-Celtic	Proto-Brythonic	Welsh
Singular	*rīganī	*rriɣėn	rhiain
Plural	*rīgan(i)yās	*rriɣaneð	rhianedd

i-stem (animate)	Proto-Celtic	Proto-Brythonic	Welsh
Singular	*mrogis	*broɣ	bro
Plural	*mrogīs	*broɣɨð2	broydd

i-stem (inanimate)	Proto-Celtic	Proto-Brythonic	Welsh
Singular	*mori	*mor	môr
Plural	*mor(i)yā	*moreð	moredd

u-stem (animate)	Proto-Celtic	Proto-Brythonic	Welsh
Singular	*sentus	*hɨnt	hynt
Plural	*sentowes	*hɨntow	hyntau

u-stem (inanimate)	Proto-Celtic	Proto-Brythonic	Welsh
Singular	*beru	*ber	bêr
Plural	*berowā	*berow	berau

s-stem	Proto-Celtic	Proto-Brythonic	Welsh
Singular	*tīros	*tir	tir
Plural	*tīresa	*tireð3	tiredd

Consonant stem	Proto-Celtic	Proto-Brythonic	Welsh
Singular	*karants	*kar	câr
Plural	*karantes	*karant	carant4

Notes:

• ¹ The plural ā-stems and plural neuter o-stems gave the same result as their respective singulars after apocope, leading to the spread of plural markers from other stem classes.
• ² From an earlier British plural *-iyes, which arose from analogy with the neuter i-stem plural *-iyā to parallel the plurals of the u-stem *-owes (m./f.) and *-owā (n.).
• ³ Through the sequence of intervocalic s > h > Ø > epenthetic j > ð.
• ⁴ The usual plural cerynt/ceraint was secondarily supplied with the o-stem ending *-oi > -ī, causing final i-affection.

Adjectives

(put information about feminines, plurals and comparatives here)