Plesiosauria

plural noun

Ple·​si·​o·​sau·​ria

ˌplēsēəˈsȯrēə

1

: a suborder of Sauropterygia comprising Mesozoic marine reptiles with dorsoventrally flattened bodies and limbs modified into paddles compare plesiosaurus

2

in some classifications : an order of Reptilia nearly coextensive with Sauropterygia

plesiosaurian

¦⸗⸗⸗¦sȯrēən

adjective or noun

plesiosauroid

-ȯˌrȯid

adjective

Word History

Etymology

New Latin, from plesi- + -sauria

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!