plural noun
Ne·​re·​idae | \ nə̇ˈrēəˌdē \

Definition of Nereidae

: a large family of predaceous marine polychaete worms that have an elongated many-segmented body with large complex parapodia on most segments and a well-defined head with paired tentacles and palps, four prostomial eyes, eight peristomial cirri, and large jaws which bite transversely and that include burrowing and free-swimming forms — see nereis

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 Nereidae

New Latin, from Nereis, type genus + -idae

Keep scrolling for more

Learn More about Nereidae

Statistics for Nereidae

Cite this Entry

“Nereidae.” Dictionary, Merriam-Webster, Accessed 31 Oct. 2020.

Comments on Nereidae

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


Test Your Vocabulary

Here Be Dragons: A Creature Identification Quiz

  • monster werewolf photo
  • Which is a synonym of werewolf?
Spell It

Can you spell these 10 commonly misspelled words?


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!