interchanging with ‑ïa‑; thus W. mw͡yar ‘blackberries’, mïaren ‘bramble’, Ir. smēr ‘blackberry’ < *smii̯ar- < *smii̯oró- (§ 65 vi (2)) : Gk. μόρον (μῶρον, Hes.) (with μ < *smi̯‑?), Lat. mōrum prob. < Gk.;—W. gw͡yal (for *gw̯w͡yal) in morw͡yal ‘laminaria’, gw̯ïal ‘twigs, osiers’ < *u̯ii̯ə‑l‑, √u̯ei̯āˣ- ‘weave’: Lat. vieo, etc.;—W. gw͡yar ‘blood, gore’ < *u̯ii̯ₑr‑: Lat. vīrus;—W. bw͡yall ‘axe’ < *bii̯ald‑, met. for *bii̯adl‑: Ir. biāil, Ml. Bret. bouhazl < *bii̯adl‑: O. N. bilda, O. H. G. bīal < *bīþl *bītl: Lat. findo, √bheied‑?—W. hw͡yad ‘duck’, Gwyn. dial. chw̯ïadan < *s‑u̯ii̯at‑, √a-u̯ei‑: Skr. váya‑ḥ ‘bird’;—W. mw͡yalch ‘ousel’ < *mesₑl‑: Lat. merula < *mesula, O.H.G. amsala, Ger. Amsel.—éso developed similarly (since post-tonic s did not give ẟ); thus *su̯ésores > chwïor-eẟ ‘sisters’, with ‑eẟ added, Bret. choarezed with two additions.
The labial changed the diphthong (Early W. *oi) to wy. Under the new accent wy remained, but became i in the present ante-penult; thus mẃyar: mïáren—*gw̯ẃyal: gw̯ïálen, a new pl. gw̯ḯal being then formed from the latter. Where the sound comes in the present ante-penult in old formations, the form is undecided ; thus O. W. guiannuin ox. ‘Spring’, Early Ml. W. guaiannu(i)n, guayanuhin a.l. i 142, also gwahanwyn do. 308, Ml. and Mn. W. gwannw͡yn, gwanw͡yn < Brit. *u̯esant‑´: Skr. vasantá‑ḥ ‘Spring’, Lat. vēr < *u̯ēsr.
(3) When the following a or o was affected, the diphthong became y or e, liable to be assimilated and lost; thus r͑yeidɏr, r͑eydɏr ‘cataracts’, heyrn ‘irons’ § 69 ii (3), Gwyn. dial. hɥ̂rn for hɥɥrn;—W. tair ‘three’ f., Ml. and O. W. teir for *tyeir (cf. breint, Seint § 103 ii (1)), Ir. teoir < *tisorés: Skr. tisráḥ; so W. pedair ‘four’ f., Ir. cetheoir < *qu̯etesorés: Skr. cátasraḥ.
Such forms as heiyrn, rheieidr are quite late and artificial. But some old re-formations occur when the diphthong stood in the present ante-penult, as deyeryn (‑yn ≡ ‑in) b.a. 12 ‘earthen’, heyernin ib. ‘of iron’, daeerin r.p. 1281, mïéri, pl. of mïáren.
(4) Secondly, the vowel following the diphthong is accented. In that case the diphthong became e or y liable to be assimilated and lost, as in (3) above. Thus W. ëog ‘salmon’ < *esā́k‑: Ir. ēo, gen. iach;—W. deall, dyall, dallt § 82 ii (3) ‘understanding’, deallt-wriaeth id., N.W. dial. dāllt < *dii̯ált- < *dii̯ā́lt- § 74 iv, met. for *dii̯ā́-tlo‑, √dhei̯ā- ‘appear, perceive’: Skr. dhyā-yati ‘thinks’, dhīraḥ ‘intelligent’; Ml. W. dyat ‘thought’ < *dii̯á‑t- with
