volo

Volo, velle, volui is irregular and has no fourth principal part, no passive and no imperative: you cannot order somebody to want something. The present tense is worth learning as a block, because volo, vis, vult, volumus, vultis, volunt refuses to follow any conjugation, and the subjunctive switches stem entirely to velim and vellem.

Two traps. First, there is a second volo, volare, volavi, "to fly", first conjugation and perfectly regular, so volat is "he flies" while vult is "he wants". Second, the second person singular vis is spelled exactly like the noun vis, "force" (rank 163), and only the sentence tells you which you have. The negative partner is nolo, nolle, nolui, and malo is "want more, prefer" - all three share the same broken paradigm. English voluntary, volition, benevolent and malevolent sit on the stem, and Latin voluntas is its abstract noun.