plural noun

in some classifications
: a division of Crustacea comprising the orders Amphipoda, Isopoda, and usually Tanaidacea in which both thorax and abdomen are segmented and there are seven pairs of thoracic appendages

Word History


New Latin, from arthr- + -ostraca

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!

Dictionary Entries Near Arthrostraca

Cite this Entry

“Arthrostraca.” Dictionary, Merriam-Webster, Accessed 28 Feb. 2024.

Love words? Need even more definitions?

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