§181. Peculiarities of Conjugation

In tenses formed upon the Perfect Stem, v between two vowels is often lost and contraction takes place.

a. Perfects in -āvī, -ēvī, -ōvī, often contract the two vowels into ā, ē, ō, respectively: as, amāsse for amāvisse; amārim for amāverim; amāssem for amāvissem; cōnsuērat for cōnsuēverat; flēstis for flēvistis; nōsse for nōvisse. So in perfects in -vī, where the v is a part of the present stem: as, commōrat for commōverat.

b. Perfects in -īvī regularly omit v, but rarely contract the vowels except before st and ss, and very rarely in the third person perfect:—

• audieram for audīveram; audīsse for audīvisse; audīstī for audīvistī; abiit for abīvit; abiērunt for abīvērunt.