Nouns in which the vowel is affected in the sg. and pl.; thus Brit. *u̯radi̯os, pl. *u̯radi̯ī > W. gwraidd ‘root’ or ‘roots’.
ii. As it is inconvenient to have the same form for sg. and pl., new distinctions grew up. These took three forms: (1) Nouns belonging to the first of the above classes had their vowel affected to form a pl.; probably some of those mentioned in § 117 i are examples of this.—(2) A pl. termination was added; thus as Lat. medicus, medicī had both become meẟyg, a new pl. meẟygon was formed; and for pl. pysg a collective pyscawt Mn. W. pysgod was used, § 123 iii.—(3) A sg. termination, m. ‑yn(n), f. ‑en(n) was added; thus gwraidd in the sg. became gwreiddyn; and as pysg continued to be used as a pl., a new sg. pysgodyn was formed from the pl. pyscawt.
Imparisyllabic Nouns.
§ 119. The W. pl. terminations are the Brit, stem-endings of imparisyllabic nouns, which were lost in the sg. representing the old nom. sg., but survived in the pl. after the loss of the pl. endings *‑es, neut. *‑a, § 113 i. Thus Lat. latrō and its Brit. pl. *latrŏnes gave W. lleidr, pl. lladron, by regular sound-change; then the ‑on of the latter and similar nouns naturally came to be regarded as a pl. ending, and was added to nouns of other declensions where a pl. sign was needed, as to meddyg, see above. Such additions were made on some analogy, mostly of meaning, sometimes of form.
u-stems.
§ 120. i. Mn. W. ‑au, Ml. W. ‑eu, O. W. ‑ou comes from Brit. *´‑ou̯es, *´‑ou̯a the pl. endings of u-stems; thus Brit. *katus, pl. *kátou̯es, gave W. cad ‘battle’, pl. cadau. This termination spread and became the commonest in W. (and Bret.). It was added to—
(1) most names of common objects; as penn-eu w.m. 41, Mn. W. pennau ‘heads’; clust-eu ib., Mn. clusti̯au ‘ears’; guefl-eu ib., Mn. gweflau ‘lips’; amrann-eu ib., r.p. 1270, Mn. amrannau, late amrantau, sg. amrant ‘eyelid’; arv-eu w.m. 7, Mn. arfau ‘arms’; tlyss-eu do. 37, Mn. tlysau, sg. tlws ‘jewel’; loggou l.l. 120 (gg ≡ ŋŋ), llongeu w.m. 39, Mn. llongau ‘ships’; badeu w.m. 39, Mn.
