mesosaur

noun

meso·​saur

ˈme|zōˌsȯ(ə)r,

ˈmē|,

|sō-

plural -s

: an extinct aquatic reptile of the genus Mesosaurus

Word History

Etymology

New Latin Mesosaurus

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!