出典:Wiktionary
From Proto-Italic *kawēō, from Proto-Indo-European *(s)kewh₁- (“to perceive, pay attention”).
Cognate with Ancient Greek κοέω (koéō), Sanskrit कवि (kaví, “wise, poet, seer, sage”), Lithuanian kavoti (“safeguard, tend”), Old Armenian ցուցանեմ (cʿucʿanem, “I show”), English show.
caveō (present infinitive cavēre, perfect active cāvī, supine cautum); second conjugation
The primary sense ("beware") may either govern a noun in the accusative or a subjunctive clause joined with nē, with the meaning "beware not to, make sure that you don't". However, the latter use became idiomatic early on with the particle nē omitted. In either case, the semantically-weakened cavĕ regularly has a short final vowel through iambic shortening. C.f. the parallel positive vidĕ (“see that, make sure to”).
1At least one rare poetic syncopated perfect form is attested.