plural noun

Definition of Heterostraci

: a class or other division of ostracoderms with widely separated nares and eyes and with an exoskeleton which may consist of a few large plates or numerous placoid scales

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 Heterostraci

New Latin, from heter- + Greek ostrakon shell, potsherd

Keep scrolling for more

Learn More about Heterostraci

Statistics for Heterostraci

Cite this Entry

“Heterostraci.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/Heterostraci. Accessed 12 December 2019.

Comments on Heterostraci

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


a period of high artistic development

Get Word of the Day daily email!

Test Your Vocabulary

Semantic Drift Quiz

  • a twisty river
  • Which of the following was once a synonym for fun?
Spell It

Can you spell these 10 commonly misspelled words?

Bee Cubed

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!