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

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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
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Dreamtime by Simon Theuma This small, commensal shrimp almost appears to be swimming over a tapestry, but in reality, the technicolor backdrop is the body of a mosaic sea star. Carlyn Kranking, Smithsonian Magazine, 25 Jan. 2024 Science defines the rat’s relationship to humans as commensal: an association between two species in which one benefits and the other is neither helped nor harmed. WIRED, 7 Oct. 2023

Word History

Etymology

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

First Known Use

1877, in the meaning defined above

Time Traveler
The first known use of commensal was in 1877

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Cite this Entry

“Commensal.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/commensal. Accessed 21 Mar. 2025.

Kids Definition

commensal

adjective
: relating to or living in a state of commensalism

Medical Definition

commensal

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

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