ii. ‑awr is common in Early Ml. W. poetry: gwaewaur b.b. 58, b.a. 9 (see fac.) ‘spears’, ysgwydawr b.a. 9 ‘shields’, cleẟyvawr, byẟinawr, llavnawr ib. ‘swords, armies, blades’; later (in prose) gwaewar w.m. 182, r.m. 85.
-awr < Brit. *‑āres < Ar. *‑ōres.
Vowel Changes.
125. The vowel changes which occur when an ending is added to form the pl. are the following:
i. Mutation § 81: brawd ‘brother’, pl. brodyr; brawd ‘judgement’, pl. brodiau; daw ‘son-in-law’, pl. dofẏon r.b.b. 68; rhaw ‘spade’, pl. rhofiau § 110 iii (1); cwrr ‘edge’, pl. cỿrrau; dɥn ‘man’, pl. dỿni̯on; sail ‘foundation’, pl. seiliau; ffau ‘den’, pl. ffeuau; gwaun ‘meadow’, pl. gweunydd; buwch ‘cow’, pl. buchod, etc. etc.
ii. Penultimate Affection § 83 iii: The endings which cause affection are ‑i, ‑ydd, ‑i̯aid, ‑i̯on: pâr, peri; dâr, deri; maer, meiri; cawr, cewri; § 122 ii (2);—caer, ceyrydd; maes, meysydd; do. (3);—cymar ‘mate’, pl. cymheiriaid; gefell r.p. 1302 ‘twin’ (< Lat. gemellus), pl. gefeilliaid; penkeirẟẏeit, anr͑eigẏon § 70 ii (2); mab ‘son’, pl. meibion, etc.; see § 128 ii.
iii. Reversion. In some cases the vowel is affected in the sg., but reverts to (or, historically speaking, retains) its original sound in the plural:
Fem. iē- or iā-stems, with pl. ending ‑edd, § 122 iv: adein b.b. 82, adain D.G. 132, 421 ‘wing’, pl. adaneẟ r.m. 155, r.b.b. 64, later affected to adenydd; celain ‘corpse’, pl. celanedd or calaneẟ r.b.b. 49; edeu, edau ‘thread’, pl. edafedd or adaveẟ r.m. 154; elain ‘fawn’, pl. elanedd or alaneẟ a.l. i 20; gw̯raig, Ml. W. gwreic, pl. gw̯rageẟ; neidr ‘snake’, pl. nadredd, anadreẟ § 21 iii, later nadroedd; r͑iein r.p. 1239, m.a. i 329b, 421b, Mn. W. rhiain D.G. 39, 95, 117, 130, 308, etc. ‘maiden’, pl. r͑ianeẟ w.m. 166, r.p. 1282, rhianedd D.G. 125, 234, 371.—Neut. io-stem: daint, pl. dannedd § 122 iii (2).—Fem. uā-stem, pl. ending ‑au: cainc ‘branch’, Ml. W. ceing w.m. 108, pl. cag̃eu b.b. 48, now cangau, see § 120 iii (2).—Neut. u-stem, pl. ending ‑au: deigr ‘tear’, pl. dagrau, see § 120 iii (1).—Mas. and fem. n-stems, pl. ending
