as·​cid·​i·​an ə-ˈsi-dē-ən How to pronounce ascidian (audio)
: any of a class (Ascidiacea) of solitary or colonial sessile tunicates having an incurrent and excurrent siphon

called also sea squirt

Word History


New Latin Ascidia, group comprising tunicates, from Ascidium, genus name, from Greek askidion, diminutive of askos wineskin, bladder

First Known Use

1823, in the meaning defined above

Time Traveler
The first known use of ascidian was in 1823

Dictionary Entries Near ascidian

Cite this Entry

“Ascidian.” Dictionary, Merriam-Webster, Accessed 27 Jan. 2023.

More from Merriam-Webster on ascidian

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

Words Named After People

  • name tags
  • Namesake of the leotard, Jules Léotard had what profession?
True or False

Test your knowledge - and maybe learn something along the way.

Solve today's spelling word game by finding as many words as you can with using just 7 letters. Longer words score more points.

Can you make 12 words with 7 letters?