D. 38 gives ieirch rh. with lleneirch; but the pl. of llannerch ‘glade’ is llennyrch; the correct reading seems to be ɥrch/llennyrch see I.G. 287.
iii. Anomalous vowel changes occur in—(1) troed ‘foot’, pl. traed § 65 ii (1); and tɥ̂ ‘house’, pl. Ml. tei, Mn. tai § 104 ii (2). The compounds of the latter have ‑tei Mn. ‑tai, or ‑tyeu Mn ‑tyau; as Mordei b.a. 1, gwindei r.p. 1202 ‘banqueting houses’; llettyeu r.p. 1274 ‘lodgings’, clafdyeu do. 1269 ‘hospitals’, hundyeu w.m. 5 ‘sleeping rooms’.
In Gwynedd ‑dai is generally accented, as beu-dắi ‘cow-houses’, pop-tắi ‘ovens’, gweith-dắi ‘workshops’; but eleuséndai ‘alms-houses’.
(2) Ml. W. biw ‘ox’ (e.g. karcharaur goruit, cul biw b.b. 90 ‘the horse is a prisoner, the ox is lean), pl. bu (e.g. can-mu w.m. 455 ‘100 oxen’); biw is also frequently pl., e.g. b.t. 59.
biw < Brit. *būu̯s < *ɡu̯ōus; bu < *bāu̯es < *ɡu̯ōu̯es; pl. biw from a re-formed *būu̯es.
(3) Other cases are carreg, pl. cerrig (for cerryg) § 77 i; crogen, cragen, pl. cregin (for cregyn) § 77 ii; asyn ‘ass’, Ml. pl. essynn w.m. 81, h.m. ii 226 (the irregularity is in the sg., where the orig. a was restored), Mn. pl. asynnod; llo ‘calf’ pl. lloi for llo-ï b.t. 59.
iv. Ml.W. pebyll m. ‘tent’ § 70 i (pl. pebylleu), Mn. pebyll sg. W.Ỻ. 216, is treated as pl. in the Bible, with a new sg. pabell f., from Wm.S.’s hypothetic pabell hwn glossing y pebyll hynn sg. 2 Cor. v 4. It is generally supposed that amws is a similar, but natural and early, analogical sg. from emys assumed to be pl. < admissus (rather *ammissus since ‑dm- > ẟf) for admissārius, but such an error is unlikely at an early period when the word was in common use ; e…y in the sg. is not unusual, e.g. ceffyl.
§ 118. i. In many parisyllabic nouns, after the loss of the Brit. endings, the pl. was not distinguished from the sg. by affection as above. These were (1) neut. nouns, whose pl. ending ‑ā did not affect; thus Brit. *arganton, pl. *argantā > W. arian, which is sg. and pl. § 133 ii.—(2) Nouns in which the vowel is not capable of i-affection (Brit. ĭ, ā, etc.) ; thus Lat. piscis, pl. pisces > W. pysc ‘fish’ sg. r.m. 131, usually pl.—(3)
