SINCE 1828
therapsid
noun
the·rap·sid
| \ thə-ˈrap-səd
\
\
Definition of therapsid
: any of an order (Therapsida) of advanced synapsid vertebrates that flourished during the Permian and Triassic periods with the last forms becoming extinct during the Cretaceous period and that are considered ancestors of the mammals
Keep scrolling for more
Comments on therapsid
What made you want to look up therapsid? Please tell us where you read or heard it (including the quote, if possible).
Test Your Vocabulary
Original Meanings Quiz
-
- Which of the following is the earliest known sense of the word awe?
Test your knowledge - and maybe learn something along the way.
TAKE THE QUIZ
Test Your Knowledge - and learn some interesting things along the way.
TAKE THE QUIZLove words? Need even more definitions?
Merriam-Webster unabridgedWords at Play
Ask the Editors
Word Games
-
Original Meanings Quiz
A quiz for the pedantic and those annoyed by them!
Take the quiz -
A Green Quiz
How many questions can you answer about the word "green"?
Take the quiz -
True or False?
Test your knowledge - and maybe learn something along the way.
Take the quiz -
Add Diction
Build a chain of words by adding one letter at a time.
Play the game
Share therapsid
Resources for therapsid