caech ‘one-eyed’: Lat. caecus ‘blind’, Goth, haihs ‘one-eyed’, Skr. kekara‑ḥ ‘squinting’ < Ar. *qaiq‑;—W. hoedl ‘lifetime, life’, Gaul. Setlo-ceni-(ae Deae): Lat. saeculum < *sai-tlo‑m § 111 vii (1); W. coed ‘wood, forest’, Gaul. Ceto-briga < *kaito‑: Goth. haiþi, O. H. G. heida, E. heath, Lat. bu-cētum (ē for ae owing to confusion with the suffix ‑ētum).
(2) Before a vowel ai fell together with ii̯, see iv below. But as in the penult, followed by e (or i), gave a new ai which gives W. oe > o § 78 i (1); thus Brit. *karaset > *karoe, caro ‘may love’. Followed by ī́ it falls together with ii̯ and gives ‑ei, as *u̯órnasīm > arnei; when the ī was unacc. it gives ‑i as *u̯órnasīm > erni § 209 vii (1).
But in the ante-penult a vowel before s drops § 113 i (2); hence *kara-se-re > kar-her ‘may be loved’.
(3) Kelt. āi > W. w͡y, as in mwy ‘greater’ < *mā́-i̯ōs or *mā́ison: Ir. mao for *mau < *mā́i̯ōs. When unaccented it was shortened and so gives oe, as prob. in Ml. W. moe Ỻ.A. 142 ‘more’.
A new āi was produced before a vowel in Brit. when ās was followed by ī or e; thus *karā́s-īt > *karāi̯īt > karwy § 183 ii (1).
A new āi might be produced before a cons. by metath. of i̯ § 100 v; thus Lat. occā́sio > W. achos > but Brit. pl. *accā́si̯ones > *accā́i̯sones > Ml. W. achwysson.
(4) W. oe > ae after w̯ or m, etc.; oe > w̯ae after g § 78 ii (2).
ii. (1) Ar. oi remained in Pr. Kelt., and appears in Ir. as ōi, ōe. In W. it became u before a consonant. Thus Ar. *oinos ‘one’ > Gk. οἰνός, οἰνή ‘ace’, O. Lat. oinos, Lat. ūnus: Ir. oen, W. un ‘one’.—W. ud in anudon ‘perjury’, Ir. oeth ‘oath’: Goth. aiþ‑s ‘oath’.—W. grug ‘heather’ for *gw̯rug (Pemb. dial. gw̯rīg), Ir. froech < *u̯roiko‑s: Gk. ἐρείκη < *u̯ereikā.
Before or after u̯ in Brit., oi became ai which gives W. oe (oy); as in gloyw ‘shiny, glossy’ < *ɡloi-u̯o‑s: Gk. γλοιός < γλοιϝος, § 92 i;—ky(h)oeẟ ‘public’ < *ky-w̯oeẟ < *ko-u̯oid‑: W. gŵyẟ ‘presence’ < *u̯eid‑, √u̯eid- ‘see’; here ‑w̯- dropped; where it remained, woe again gave wae § 78 ii (2); thus gwaethaf for *gwoethaf < *u̯aidisamos < *u̯oidisamos < *u̯o-ed-isamos < *upo-ped-isₑmo‑s § 148 i (5).
(2) Before a back vowel oi gave W. w͡y; as *‑oi̯an > *‑wy‑n > ‑wn § 180 iii (1); cf. § 76 v (4). But before i or e the i̯
