cupio.

From Proto-Italic *kupjō. According to the LIV, from Inherited from Proto-Indo-European *kup-yé-ti, from *kwep- (“to smoke, boil, move violently”). If this theory is accepted, the term has an exact parallel in Sanskrit कुप्यति (kupyati, “to become agitated, bubble up”). De Vaan, however, explains the word as a derivative of an athematic i-present *kup-i- of the same root. Schrijver, who also adopts the i-present explanation, suggests that the full-grade of the suffix of this i-present (e.g. a form of the shape *kup-ey-) could explain the forms with the long vowel ī, such as cupīvī. Schrijver does, however, also mention a possible alternative explanation—that the perfect form was created analogically after fourth conjugation terms such as audīvī. Weiss alternatively suggests that perfect forms in -īvī spread across verbs with similar semantics, all pertaining to the notion of "seeking." For instance, compare arcessō (“to summon, invite”), arcessīvī; petō (“to ask, beg”), petīvī; and quaerō (“to search”), quaesīvī. Cognate with Lithuanian kūpėti (“to boil over”) and Old Church Slavonic кꙑпѣти (kypěti, “to boil”).