ascidium \ascid"ium\ a^ssi^d"i^u^m, n.; pl.
   ascidia -.a. nl., fr. ascus. see ascus.
   1. bot. 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.
      1913 webster

   2. pl. zool. 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.
      1913 webster
see also:
ascidia ascus