dropped § 100 vi, and o before the vowel developed like u before a vowel, that is, as ou̯; thus *dó esō > *dói̯ǖ > *dóī > *dóu̯ī > *deu § 76 v (1), whence deuaf § 193 x (5); and *do eset > *doi̯et > *doet > *dou̯et > daw, or without diphthongization *do-et > do, see ib.; so *moi estō > *mo estī > *mo ys > moes § 200 ii. Followed by ī after the accent it gives ‑i, as in ‑ẟi f. sing. ‘to her’ < *´‑doi̯ī < *´‑do-sī § 210 x (1).
(3) Ar. ōi gave Kelt. āi and developed accordingly.
iii. (1) Ar. ei remained in Pr. Kelt. In Gaul. it is written e or ει, as Devo-gnata, Δειουονα. In Ir. it appears as ē or īa. In W. before a consonant it became w͡y. Thus W. gŵyẟ ‘presence’ for *gw̯ŵyẟ < Ar. *u̯eid- § 63 iv;—mor-dw͡y ‘sea voyage’ < *mori-teig- § 103 ii (1), etc.
In Brit. and Gaul. it was probably sounded as ẹi̯. Latin ē which was sounded ẹ̄, was identified with this sound in Brit., and shared its development in W., thus rēte > rhwyd, rēmus > rhwyf, plēbem > plwyf, cēra > cwyr, etc. Lat. oe which seems to have varied from ö to ẹ appears in W. as i, oe or w͡y, as ciniaw ‘dinner’, poen ‘pain’, cwyn ‘supper’.
(2) Before a vowel ei fell together with ii̯, see below.
(3) Ar. ēi before a vowel > Kelt. ī > W. i. Thus W. dī́od, Ml. diawt ‘drink’ < *dhēi-āti‑s, √dhēi- ‘suck’.—W. llī́aws ‘multitude’, Bret. liez < Brit. *līā́ssās < *līāstāts < *(p)līōs-tāts, a noun in *‑tāt- from the cpv. *plē-i̯ōs: Lat. insc. pleores, Gk. πλείων. Before Kelt. o it becomes u, as in llüosog, Ml. lluossauc < Brit. *līu̯ossā́ko‑s an extension *līu̯osso‑s < *(p)līos-to‑s an adj. formed from *plē-i̯ōs like Lat. honestus from honōs; see § 76 ix (2), § 74 i (2), § 169 iii (3). Before a consonant ēi > ē giving Kelt. ī, W. i.
iv. ai and ei fell together with ii̯ before vowels. After the accent the i̯ became ẟ, in other positions it remained as i̯. Thus:
(1) Accented íi̯ (or ái̯ or éi̯), which is generally in the penult, but may be ante-penultimate, gives W. ‑yẟ; thus W. rhyẟ ‘free’ < *príi̯os: Goth. freis, Eng. free;—trefyẟ ‘towns’ < *trebíi̯es;—trydyẟ ‘third’ m. < *tritíi̯os; with ‑a in the ult. it gives ‑eẟ, as trydeẟ ‘third’ f. < *tritíi̯ā. In the ante-penult ‑yẟ‑, as W. ysbyẟad ‘thorn’: Ir. scē, gen. pl. sciad.
(2) Post-tonic ´‑ii̯ gave *ai̯i̯, which became oeẟ, § 62 i (2);
