Definition of ascidian
: any of a class (Ascidiacea) of solitary or colonial sessile tunicates having an incurrent and excurrent siphon —called also sea squirt
Origin and Etymology of ascidian
New Latin Ascidia, group comprising tunicates, from Ascidium, genus name, from Greek askidion, diminutive of askos wineskin, bladder
First Known Use: 1823See Words from the same year
Seen and Heard
What made you want to look up ascidian? Please tell us where you read or heard it (including the quote, if possible).