plural noun Ac·an·tho·dii \ˌaˌkanˈthōdēˌī, ˌakən-\

Definition of Acanthodii

  1. :  a subclass of Placodermi comprising primitive Paleozoic fishes having the anterior margin of each fin supported by a stout spine and often having one or more pairs of spines similar to the fin spines along the lower lateral part of the body between the paired fins of each side

Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Join MWU now and get access to America’s largest dictionary, with:

  • 300,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

Origin and Etymology of acanthodii

New Latin, from Acanthodes

First Known Use: 1851

Seen and Heard

What made you want to look up Acanthodii? Please tell us where you read or heard it (including the quote, if possible).


a trip made at another's expense

Get Word of the Day daily email!