commensal

American  

[kuh-men-suhl] / kəˈmɛn səl /

adjective

1. eating together at the same table.

2. Ecology. (of an animal, plant, fungus, etc.) living with, on, or in another, without injury to either.

3. Sociology. (of a person or group) not competing while residing in or occupying the same area as another individual or group having independent or different values or customs.

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noun

1. a companion at table.

2. Ecology. a commensal organism.

commensal British  

/ ˌkɒmɛnˈsælɪtɪ, kəˈmɛnsəl /

adjective

1. (of two different species of plant or animal) living in close association, such that one species benefits without harming the other

2. rare of or relating to eating together, esp at the same table

   commensal pleasures

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noun

1. a commensal plant or animal

2. rare a companion at table

Other Word Forms

• commensalism noun
• commensality noun
• commensally adverb

Etymology

Origin of commensal

First recorded in 1350–1400; Middle English word from Medieval Latin word commēnsālis. See com-, mensal ²

Example Sentences

The early human-leopard cat relationship was essentially "commensal" where two species live alongside each other harmlessly, said Prof Shu-Jin Luo of Peking University in Beijing.

From BBC • Nov. 27, 2025

Microbes in the gut live in a delicate balance, and commensal bacteria provide important benefits to the body by breaking down nutrients, producing metabolites, and -- importantly -- protecting against pathogens.

From Science Daily • Feb. 2, 2024

UAB researchers Hyunmin Koo, Ph.D., and Casey D. Morrow, Ph.D., focused on the commensal microbe Bacteroides vulgatus, one of the most common species found in healthy guts.

From Science Daily • Oct. 13, 2023

"The number of commensal bacteria in very low compared to the gut so it is possible that they don't do much," Persat said.

From Salon • Aug. 5, 2023

Either there was soil deeper down, or this species of tree was a remarkable in­stance of a commensal or a parasite.

From "Life of Pi" by Yann Martel