com·​men·​sal | \kə-ˈmen(t)-səl \

Definition of commensal 

: of, relating to, or living in a state of commensalism commensal organisms

Keep scrolling for more

Other Words from commensal

commensal noun
commensally \kə-​ˈmen(t)-​sə-​lē \ adverb

Did You Know?

Commensal types, be they human or beast, often "break bread" together. When they do, they are reflecting the etymology of commensal, which derives from the Latin prefix com-, meaning "with, together," jointly and the Latin adjective mensalis, meaning "of the table." In its earliest English uses, "commensal" referred to people who ate together, but around 1870, biologists started using it for organisms that have no use for a four-piece table setting. Since then, the scientific sense has almost completely displaced the dining one.

Examples of commensal in a Sentence

Recent Examples on the Web

In payment, the plants feed their commensal friends with sugars. Jason Pontin, WIRED, "The 19th-Century Crank Who Tried to Tell Us About the Microbiome," 15 June 2018 This turned out to be because the antibiotics also diminished the numbers of tuft cells in the colon; only they, and not commensal bacteria, are required for norovirus infection. Diana Gitig, Ars Technica, "We’ve found the cells norovirus targets—we just don’t know what they do," 14 Apr. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'commensal.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of commensal

1877, in the meaning defined above

History and Etymology for commensal

Middle English, from Medieval Latin commensalis, from Latin com- + Late Latin mensalis of the table, from Latin mensa table

Keep scrolling for more

Learn More about commensal

Listen to Our Podcast about commensal

Statistics for commensal

Look-up Popularity

Time Traveler for commensal

The first known use of commensal was in 1877

See more words from the same year

Keep scrolling for more

More Definitions for commensal


com·​men·​sal | \kə-ˈmen(t)-səl \

Medical Definition of commensal 

: of, relating to, or living in a state of commensalism

Other Words from commensal

commensal noun
commensally \-​sə-​lē \ adverb

More from Merriam-Webster on commensal

Rhyming Dictionary: Words that rhyme with commensal

Comments on commensal

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


a knickknack or trinket

Get Word of the Day daily email!

Test Your Vocabulary

Find the Cousins

  • a-large-tree-with-many-branches
  • Which pair shares a common word ancestor?
Name That Thing

Test your visual vocabulary with our 10-question challenge!


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!