Origin: NL, fr. Ascus. See Ascus.
1. (Science: botany) a pitcher-shaped, or flask-shaped, organ or appendage of a plant, as the leaves of the pitcher plant, or the little bladderlike traps of the bladderwort (Utricularia).
2. (Science: zoology) a genus of simple ascidians, which formerly included most of the known species. It is sometimes used as a name for the ascidioidea, or for all the tunicata.