Pronunciation: (tOO'ni-kit, -kāt", tyOO'-),[key] —n. Zool.any sessile marine chordate of the subphylum Tunicata (Urochordata), having a saclike body enclosed in a thick membrane or tunic and two openings or siphons for the ingress and egress of water.
—adj.Also,tu'ni•cat"ed. 1. (esp. of the Tunicata) having a tunic or covering.
2. of or pertaining to the tunicates.
3. Bot.having or consisting of a series of concentric layers, as a bulb.