plural noun
The·​ria | \ˈthirēə, ˈthēr-\

Definition of Theria 

(Entry 1 of 2)

in some classifications

: a subclass of Mammalia comprising the higher mammals and including the Pantotheria, Metatheria, and Eutheria and excluding the Prototheria and Allotheria


Definition of -theria (Entry 2 of 2)

: beasts : animals in names of higher taxa of mammalian forms Prototheria

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!

Other Words from Theria

Plural noun

therian \ -​ən \ noun or adjective

History and Etymology for Theria

Plural noun

New Latin, from Greek thēria, plural of thērion wild animal

Noun combining form

New Latin, from Greek thēria, plural of thērion

Keep scrolling for more

Learn More about Theria

Statistics for Theria

Look-up Popularity

Comments on Theria

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


obstinately defiant of authority

Get Word of the Day daily email!

Test Your Vocabulary

Autumn Words of the Day 2018

  • a-top-down-image-of-road-through-an-autumn-forest
  • Which is a synonym of fugacious?
True or False

Test your knowledge - and maybe learn something along the way.


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!