§177. Perfect Stem
The Perfect Stem is formed as follows:—
a. The suffix v ( u) is added to the verb-stem: as, vocā-v-ī, audī-v-ī; or to the root: as, son-u-ī (sonā-re, root SON), mon-u-ī ( monē-re, MON treated as a root).1
b. The suffix s is added to the root: as, carp-s-ī (CARP), tēx-ī (for tēg-s-ī, TEG).2
c. The root is reduplicated by prefixing the first consonant—generally with ĕ, sometimes with the root-vowel: as, ce-cid-ī ( cadō, CAD), to-tond-ī ( tondeō, TOND).
d. The root vowel is lengthened, sometimes with vowel change: as, lēg-ī ( lĕg-ō), ēm-ī ( ĕm-ō), vīd-ī ( vĭd-e-ō), fūg-ī ( fŭg-i-ō), ēg-ī ( ăg-ō).
e. Sometimes the perfect stem has the same formation that appears in the present tense: as, vert-ī ( vert-ō), solv-ī ( solv-ō).
f. Sometimes the perfect is formed from a lost or imaginary stem: as, petī-v-ī (as if from †peti-ō, †petī-re, PET).
J. H. Allen and J. B. Greenough, New Latin Grammar (Boston: Ginn, 1903). Text provided under a CC BY-SA license by Perseus Digital Library, http://www.perseus.tufts.edu, with funding from the National Endowment for the Humanities.