[107]. ([a.]) In final syllables unaccented original e before s and t was weakened to i: as, salūtis, of safety, from older salūtes ([507]).
([b.]) Final i became e: as, ante for *anti (Greek ἀντί and anti-cipāre); nominative singular mare, from the stem mari- ([526]).
([c.]) In final syllables o before consonants changed to u except when preceded by u or v: as, fīlius, son, for old Latin fīlios ([452]); ferunt, they carry, for older feront; femur, thigh, nomin. sg. from the stem femor- ([489]); genus, kind, for *genos, Greek γένος; but vīvont, they live; salvom, safe. Not long before the beginning of our era o here also changed to u and appears to have coalesced with the preceding v (Quint. 1, 7, 26): as, in inscriptions: INGENVS (nomin. sg.) for ingenuos; SERVM, slave (acc. sg.), for servom; NOVM for novom, something new; so also boum, oxen (gen. pl.), for bovom ([494]). But inasmuch as the majority of forms in the paradigms of these words retained their v, it was restored in most cases, by analogy, to the forms which had lost it: as, servum for serum, because of servī, servō, etc.; vīvunt for vīunt, because of vīvō, vīvis, vīvit, etc.
([d.]) When the stems fac- (facere, do), cap- (capere, take) appear as second members of compounds, their a changes in final syllables to e: as, artifex, artisan; auceps, bird-catcher. After the analogy of these words, compounds with dīcere and īre have e in the nom. sg.: as, iūdex, iūdicis, judge (from iūs and dīcere); comes, companion (from com, with, and īre); see [136], 2.
[WEAKENING OF DIPHTHONGS IN UNACCENTED SYLLABLES.]
[108]. Diphthongs, whether medial or final, are treated alike in atonic syllables.
([a.]) Atonic ei, oi, and ai (ae) became ī: as, lupī, wolves (nom. pl.), for *lupoi (Gr. λύκοι); bellī, in war (loc. sg., [460], [1338]), for *bellei (Greek οἴκει) or *belloi (Greek οἴκοι); éxīstimō, I consider, from aestimō; cóncīdō, I strike down, from caedō; Cicero, O. 159, mentions inīcum, unfair, for *ínaecum, and concīsum for *cóncaesum; so also, probably, hīc, this, arose from hoic ([662]) when used as a proclitic ([92]).
([b.]) Atonic ou and au became ū: as, ínclūdō, I include, from claudō; áccūsāre, to accuse, from causa.
[109]. There are not a few cases in which the atonic vowel does not conform to the rules given above ([102-108]). These are usually compounds which show the vowel of the simple verb. Some of these were formed at a time when the early recessive accent was no longer in force and consequently there was no cause for weakening; in others the vowel of the simple verb was by analogy substituted for the weakened vowel of the compound: as, appetō, I strive after, from petō, which ought to have i like colligō, collect, from legō; intermedius, intermediate, but dīmidius, half; dēfraudāre, to cheat, by the side of dēfrūdāre from fraudāre; instead of the common redarguō, I refute, Scipio Africanus minor Pauli filius (185-129 B.C.) said rederguō, and pertīsum for pertaesum, but both Cicero (O. 159) and Lucilius discountenance pertīsum as the sign of a pedantic prig. In a few cases the reverse process took place, and the weakened vowel which arose in the compound was transferred to the simple verb: as, clūdō, I close ([958]), for claudō, which owes its ū to compounds like occlūdō. For a case where the vowel of the preceding syllable acted as a stay to the expected change, see [104], d.