Hes·​per·​or·​nis | \ˌhespəˈrȯrnə̇s\

Definition of Hesperornis 

: a genus of swimming birds (order Hesperornithiformes) from the Cretaceous of Kansas that resemble loons in form, that have teeth in each jaw implanted in a long groove, and that in some cases exceed five feet in length

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 Hesperornis

New Latin, from Greek hesperos western + New Latin -ornis

Keep scrolling for more

Learn More about Hesperornis

Share Hesperornis

Statistics for Hesperornis

Look-up Popularity

Comments on Hesperornis

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


the figure or shape of a crescent moon

Get Word of the Day daily email!

Test Your Vocabulary

Late Autumn 2018 Words of the Day Quiz

  • frosted-autumn-leaves
  • Which is a synonym of yahoo?
Name That Thing

Test your visual vocabulary with our 10-question challenge!

Word Winder's CrossWinder

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!