• synonyms


[kuh-men-suh l]
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  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.
  1. a companion at table.
  2. Ecology. a commensal organism.

Origin of commensal

First recorded in 1350–1400; Middle English word from Medieval Latin word commēnsālis. See com-, mensal2
Related formscom·men·sal·ism, nouncom·men·sal·i·ty [kom-en-sal-i-tee] /ˌkɒm ɛnˈsæl ɪ ti/, nouncom·men·sal·ly, adverb
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for commensal

Historical Examples

  • The shells of hermit-crabs serve frequently as the home of other animals which live with them a commensal life.

    The Sea-beach at Ebb-tide

    Augusta Foote Arnold

  • Pinnixa cylindrica, a related species, lives in the tubes of large annelid worms as a commensal.

    The Sea-beach at Ebb-tide

    Augusta Foote Arnold

  • My specimen was not commensal, but was hidden among the mollusc tubes.

  • Chance must play a very considerable part in first bringing symbiotic or commensal partners together.

  • They are supposed to be commensal in habit and live in the deeper water offshore.

    The Sea-beach at Ebb-tide

    Augusta Foote Arnold

British Dictionary definitions for commensal


  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 tablecommensal pleasures
  1. a commensal plant or animal
  2. rare a companion at table
Derived Formscommensalism, nouncommensality (ˌkɒmɛnˈsælɪtɪ), nouncommensally, adverb

Word Origin

C14: from Medieval Latin commensālis, from Latin com- together + mensa table
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for commensal


"one who eats at the same table" (as another), c.1400, from Old French commensal (15c.), from Medieval Latin commensalis, from com- "together" (see com-) + mensa (genitive mensalis) "table" (see mesa). Biological sense attested from 1870.

Online Etymology Dictionary, © 2010 Douglas Harper

commensal in Medicine


  1. Of, relating to, or characterized by a symbiotic relationship in which one species is benefited while the other is unaffected.
  1. An organism participating in a symbiotic relationship in which one species derives some benefit while the other is unaffected.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.