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197. Several verbs add some of the personal endings of the present system directly to the root,1 or combine two verbs in their inflection. These are called Irregular Verbs. They are sum, volō, ferō, edō, , , queō, fīō, and their compounds.

The conjugation of sum has already been presented in § 170.

198. Sum is compounded without any change of inflection with the prepositions ab, ad, , in, inter, ob, prae, prō (earlier form prōd), sub, super.

a. In the compound prōsum (help), prō retains its original d before e.

irregular verb prōsum present system synopsis

irregular verb prōsum perfect system synposis

b. Sum is also compounded with the adjective potis, or pote (able), making the verb possum (be able, can). Possum is inflected as follows.2

irregular verb possum present system synopsis

irregular verb possum perfect system synopsis


1. These are athematic verbs, see § 174.2.
2. The forms potis sum, pote sum, etc. occur in early writers. Other early forms are potesse; possiem, -ēs, -et; poterint, potisit (for possit); potestur and possitur (used with a passive infinitive, cf. § 205.a).

Suggested Citation

Meagan Ayer, Allen and Greenough’s New Latin Grammar for Schools and Colleges. Carlisle, Pennsylvania: Dickinson College Commentaries, 2014. ISBN: 978-1-947822-04-7.