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[myoo-choo-uh-liz-uh m] /ˈmyu tʃu əˌlɪz əm/
a relationship between two species of organisms in which both benefit from the association.
the doctrine that the interdependence of social elements is the primary determinant of individual and social relations, especially the theory that common ownership of property, or collective effort and control governed by sentiments of brotherhood and mutual aid, will be beneficial to both the individual and society.
Sociology. the force or principle of mutual aid.
Origin of mutualism
First recorded in 1860-65; mutual + -ism
Related forms
mutualist, noun
mutualistic, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for mutualist
Historical Examples
  • Notably, the gilt catfish, which would undoubtedly die if deprived of its mutualist, the Gyropeltes.

    The Dawn of Reason James Weir
British Dictionary definitions for mutualist


another name for symbiosis
Derived Forms
mutualist, noun, adjective
mutualistic, adjective
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
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Word Origin and History for mutualist



1849, in reference to the doctrine of French anarchist/socialist Pierre-Joseph Proudhon (1809-1865), from French mutuellisme. In biology, from 1876, from mutual + -ism.

Online Etymology Dictionary, © 2010 Douglas Harper
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mutualist in Medicine

mutualist mu·tu·al·ist (myōō'chōō-ə-lĭst)
See symbion.

mutualism mu·tu·al·ism (myōō'chōō-ə-lĭz'əm)
A symbiotic relationship in which both species benefit.

mu'tu·al·is'tic adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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mutualist in Science
A symbiotic relationship in which each of the organisms benefits. ◇ In obligate mutualism the interacting species are interdependent and cannot survive without each other. The fungi and algae that combine to form lichen are obligate mutualists. ◇ In the more common facultative mutualism the interacting species derive benefit without being fully dependent. Many plants produce fruits that are eaten by birds, and the birds later excrete the seeds of these fruits far from the parent plant. While both species benefit, the birds have other food available to them, and the plants can disperse their seeds when the uneaten fruit drops. Compare amensalism, commensalism, parasitism.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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