| ascidian | (n) minute sedentary marine invertebrate having a saclike body with siphons through which water enters and leaves |
| ascidian tadpole | (n) free-swimming larva of ascidians; they have a tail like a tadpole that contains the notochord |
| Ascidian | n. [ Gr. &unr_; bladder, pouch. ] (Zool.) One of the Ascidioidea, or in a more general sense, one of the Tunicata. Also as an adj. [ 1913 Webster ] |