| Noun | 1. | Ascidiaceae - sometimes classified as an order: sea squirtssubphylum Tunicata, subphylum Urochorda, subphylum Urochordata, Tunicata, Urochorda, Urochordata - tunicates ascidian - minute sedentary marine invertebrate having a saclike body with siphons through which water enters and leaves ascidian tadpole - free-swimming larva of ascidians; they have a tail like a tadpole that contains the notochord class - (biology) a taxonomic group containing one or more orders |