plural noun

in many classifications
: a major division of the animal kingdom comprising all bilateral animals (such as the chordates) that lack ectomesoderm and have indeterminate cleavage and a mouth that does not arise from the blastopore

Word History


New Latin, from deuter- entry 1 + -stomia

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 Deuterostomia

Cite this Entry

“Deuterostomia.” Dictionary, Merriam-Webster, Accessed 18 Jul. 2024.

Love words? Need even more definitions?

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