plural noun
Cas·​sid·​i·​dae | \ kəˈsidəˌdē, ka-\

Definition of Cassididae

: a family of usually large marine gastropod mollusks (order Pectinibranchia) having thick heavy shells of which many are used for making cameos — see helmet shell

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.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

History and Etymology for Cassididae

New Latin, from Cassid-, Cassis, type genus + -idae

Keep scrolling for more

Learn More about Cassididae

Share Cassididae

Statistics for Cassididae

Look-up Popularity

Comments on Cassididae

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


marked by fawning attentiveness

Get Word of the Day daily email!

Test Your Vocabulary

What did you just call me?! A Quiz

  • rows-of-various-emoji
  • If a member of the audience describes your speech as bombastic, does that person mean it is:
Spell It

Can you spell these 10 commonly misspelled words?

Add Diction

Test Your Knowledge - and learn some interesting things along the way.


Love words? Need even more definitions?

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