N0125700 (nŏk-tûr′nəl)adj.1. Of, relating to, or occurring in the night: nocturnal stillness.2. Botany Opening at night. Used of flowers.3. Zoology Most active at night: nocturnal lizards.[Middle English, from Old French, from Late Latin nocturnālis, from Latin nocturnus, from nox, noct-, night; see nekw-t- in Indo-European roots.]noc·tur′nal·ly adv.Thesaurus