Merriam-Webster Logo
SINCE 1828
dictionary thesaurus view recents

Prototheria

plural noun
Save Word
Pro·​to·​the·​ria

Definition of Prototheria

: a subclass of Mammalia that is coextensive with Monotremata or in some classifications includes both Monotremata and Allotheria and that is represented in the recent fauna solely by the egg-laying platypus and echidnas

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 Prototheria

New Latin, from prot- + -theria

Keep scrolling for more

Learn More about Prototheria

Statistics for Prototheria

Cite this Entry

“Prototheria.” The Merriam-Webster.com Dictionary, Merriam-Webster Inc., https://www.merriam-webster.com/dictionary/Prototheria. Accessed 28 January 2020.

Comments on Prototheria

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

Show Comments  Hide Comments 

WORD OF THE DAY

diligent

Listen to the pronounciation of diligent

showing steady, earnest care and effort

Get Word of the Day daily email!

Test Your Vocabulary

January 2020 Words of the Day Quiz

  • image1642096650
  • Which is a synonym of bonhomie?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Add Diction

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

TAKE THE QUIZ
Love words? Need even more definitions?

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

Words at Play
Ask the Editors
Word Games