‘split’;—so sarn ‘causeway’: Skr. stīrṇáḥ ‘strewn’, √sterō‑;—carn ‘hoof’, Galat. κάρνον ‘trumpet’: √k̑erāˣ(u̯)‑;—teneu ‘thin’, Corn. tanow, Ir. tana: Gk. τανυ‑, Lat. tenuis, Skr. tanú‑ḥ, all < Ar. *tₑnu‑; hafal ‘like, equal’, Ir. samail ‘likeness’ < *sₑmₑl‑: Lat. similis;—ganed ‘was born’ < *g̑ₑn‑, *√g̑enē‑.
R-grade before u̯: W. carw̯ deer ' < *k̑ₑru̯-os: Lat. cervus < *k̑eru̯-os;—marw̯ ‘dead’: Lat. mortuus § 204 ii (5);—before i̯: W. myned § 100 iv.
The forms l̥, r̥, m̥, n̥ are generally classed as V-grade; but the vowel of the syllable cannot be said to have vanished when it has converted the consonant r into the vowel r̥. In fact r̥ is the form that ₑr takes before a consonant, and must therefore be the same grade.
iv. The treatment of the diphthongs ei, eu (properly ei̯, eu̯) is parallel, i̯ and u̯ corresponding to l, r, m, n, and vocalic i, u to vocalic l̥, r̥, m̥, n̥. Thus:
| V | R | F | F° | L | L° |
| i̯ | i, (ₑi̯ >) ii̯ | ei̯ | oi̯ | ei̯ | oi̯ |
| u̯ | u, (ₑu̯ > ) uu̯ | eu̯ | ou̯ | eu̯ | ou̯ |
The R-grade forms i, u occur before consonants only; the forms ₑi̯, ₑu̯, which became ii̯, uu̯, occur before vowels.
Examples: V-grade: W. berw̯i ‘to boil’, Lat. ferveo < *bheru̯‑, √bhereu̯‑;—W. duw ‘god’ < *dw͡yw̯, Lat. deus both < *dei̯u̯-os, √dei̯eu̯‑, vii (4).
√u̯ei̯d- ‘see, know’:—R: gwedd ‘aspect’ < *u̯id-ā; gw̯ŷs ‘summons’, gw̯ŷs ‘it is known’, both < *u̯itˢt- < *u̯id‑t‑; Lat. vid-eo;—F: gŵydd ‘presence’ < *u̯ei̯d‑, arw͡ydd ‘sign’ < *pₑri-u̯eid‑; Gk. εἴδομαι;—F°: Gk. οἶδα < *u̯oi̯d-a.
√k̑leu̯- ‘hear’:—R: clod ‘praise’ < *k̑lu-tó‑m § 66 v; Gk. κέ-κλυ-θι;—F: clust ‘ear’ < *k̑leu‑t‑st- § 96 ii (3).
√deu̯k- ‘lead’:—R: dyg-af ‘I bring’, dwg ‘brings’ < *duk‑; dwyn ‘to bring’ < *duk‑n‑;—F: Lat. dūco, O. Lat. douc-o, Goth. tiuh-an < *deuk‑;—L°: dug 'brought' < *(du)-dōuk‑, § 182 ii (2).
The V-grade disappears between consonants; see √qonei̯d- vii (4) √geneu̯- ib.; see viii (2) and § 100 ii (2).
v. (1) As seen above, Ar. had the vowel e interchanging with o; the vowels i and u are secondary, being vocalized forms of i̯ and u̯.
(2) a occurred in Ar. only in special cases, which Meillet, Intr.² 139 gives thus: 1. in child-language, as Skr. tata, Gk. τάτα, Lat. tata, W. tada; 2. in certain isolated words, possibly borrowed, as Lat. faba; 3. in a few endings, as 3rd sg. mid. *‑tai, Gk. ‑ται, Skr. ‑te; and 4. initially, interchanging with zero, as Gk. ἀστήρ: Lat. stella, W. seren, E. star.
As shown by Meillet (ib. 140) initial a- may coexist with the F- or L-grade of the following syll., as in Gk. ἀ(ϝ)έξω with F *u̯eg- beside αὔξω, Lat. augeo with V *u̯g‑; cf. ἀστήρ. This seems to imply that a- might be a movable preformative, but it does not prove that it was
