plural noun Cid·a·roi·da \ˌsidəˈrȯidə\

Definition of Cidaroida

  1. :  the oldest surviving order of sea urchins containing the most primitive of living forms, all lacking peristomial gills and sphaeridia but having an apically located anus — see cidaridae

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 cidaroida

New Latin, from Cidaris + -oida

Seen and Heard

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


to help become familiar with something

Get Word of the Day daily email!