The most fundamental verb in Greek, εἰμί expresses existence, identity, and predication. Its paradigm is wildly irregular, drawing from multiple ancient roots: present εἰμί, imperfect ἦν, future ἔσομαι. Dialectal forms abound—Aeolic ἔμμι, Doric ἐντί, Epic εἰμέν. The third-person ἐστί can be existential ('there is'), copular ('the man is wise'), or possessive ('I have' = μοί ἐστι). No verb sees more use or shows more morphological irregularity across Greek dialects.