‘lion’ < leo; pydew ‘pit’ < puteus; olew ‘oil’ < oleum. But Lat. i in the same position gave i̯ which affected the vowel: W. yspeil < spolium; so sometimes e: W. cŷn ‘chisel’ < Lat. cuneus.
viii. (1) In final syllables, lost in W., Ar. ai, oi, ei became ī in Brit. and Gaul.; thus the nom. pl. ending of noun o-stems, which in Pr. Kelt., as in Lat. and Gk., was *‑oi (instead of Ar. *‑ōs), became ‑ī (though ‑oi also survives in a North Italian Kelt. insc.: Tanotaliknoi, Rhys, CIFI. 60); thus Brit. *bardos pl. *bardī > W. bardd, pl. beirdd.
‑āi unaccented > ai > ī, thus Gaul. Βηλησαμι dat. of a name whose nom. occurs as Belisama; ōi > ūi, in Pr. Kelt, later ū, § 60, cf. Ir. dat. fiur ‘to a man’ < dat. *u̯irōi; ‑ēi doubtless gave ‑ī.
(2) But in monosyllables Ar. ‑ai, ‑oi, ‑ei remained in Kelt., and developed as follows in W.:
‑ai > ‑oe, thus Ar. *u̯ai > *gwoe > gwae § 78 ii (2).
‑ei > wy; W. wy ‘they’ < *ei: Ir. ē.
‑oi > wy; W. pwy ‘who?’ < *qu̯o-i = Lat. quī § 163 vi; when unaccented it became eu (O. W. ou, oi) § 78 iii, thus Ar. *moi, *toi > W. meu, teu § 161 iv.
§ 76. i. The Ar. diphthongs au, eu, ou were distinct in Pr. Kelt., but tended later to become one sound, which is written ou. In Gaul. eu was still written as well as ou in forms having original eu, as in teuto- beside τοουτιους and Neviod… beside Noviodunum; we also find αυ, iii (4). In Brit. we may assume ou for all three. In W. it takes a variety of forms according to its position. The same development is shared by uu̯ whether from Ar. uu̯ § 63 iv or from Lat. u before a vowel.
ii. (1) Before a consonant, except s, the diphthong became u (≡ ü) in W., ūa in Ir. Thus W. tud ‘people, country’, Ir. tūath < *teutā, Gaul. teuto‑: Goth. þiuda, etc.;—W. rhudd ‘red’, Ir. rūad < *roudh-os, Gaul. Roud-ius: Goth. rauþs;—W. cudd ‘hidden’, cuddio ‘to hide’ < *qeudh‑: Gk. κεύθω, O. E. hȳde, E. hide;—W. bugail ‘shepherd’ < *bou-koli̯ós < *ɡu̯ou-qoli̯ós: Gk. βουκόλος.
In Brit. it was probably sounded ọu̯; and Lat ō (≡ ọ̄) and ū shared its development; thus W. ffurf < Lat. fōrma; mur < Lat. mūrus, etc.
(2) But original eus gives W. ew, as rhew ‘ice’ < *preus‑:
