ich·​thyo·​sau·​rus | \ -rəs\

Definition of ichthyosaurus

1 capitalized : the type genus of Ichthyosauridae comprising highly variable Jurassic ichthyosaurs and originally including most of the later ichthyosaurs most of which are now placed in other genera
2 plural -es : any reptile of the genus Ichthyosaurus

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 ichthyosaurus

New Latin, from ichthy- + -saurus

Keep scrolling for more

Learn More about ichthyosaurus

Share ichthyosaurus

Statistics for ichthyosaurus

Look-up Popularity

Comments on ichthyosaurus

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


marked by fawning attentiveness

Get Word of the Day daily email!

Test Your Vocabulary

What did you just call me?! A Quiz

  • rows-of-various-emoji
  • If a member of the audience describes your speech as bombastic, does that person mean it is:
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Add Diction

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!