'Pilidium' definitions:

Definition of 'Pilidium'

From: GCIDE
  • Pilidium \Pi*lid"i*um\, n.; pl. Pildia. [NL., fr. Gr. ?, dim. of ? a cap.] (Zool.) The free-swimming, hat-shaped larva of certain nemertean worms. It has no resemblance to its parent, and the young worm develops in its interior. [1913 Webster]