Pen·​tam·​er·​us | \ pen‧ˈtamərəs\

Definition of Pentamerus

: a genus (the type of the family Pentameridae) comprising Paleozoic brachiopods of the order Protremata abundant in the Silurian and having the shell rostrate and oval or somewhat pentagonal with its cavity divided by two internal vertical ridges and a spondylium in each valve

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 Pentamerus

New Latin, from penta- (from Greek) + -merus -merous

Keep scrolling for more

Comments on Pentamerus

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


miscellaneous remnants or debris

Get Word of the Day daily email!

Test Your Vocabulary

The Exceptions Quiz III

  • one green toy robot amidst many red toy robots
  • Which of these words does not mean "nonsense"?
True or False

Test your knowledge - and maybe learn something along the way.

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!