Any of various sedentary tunicates of the class Ascidiacea, having a transparent sac-shaped body with two siphons. Also called ascidian.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.