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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.
1860-65; mutual + -ism
Related forms
mutualist, noun
mutualistic, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for mutualistic
  • The corals and algae have a mutualistic relationship.
  • Dynamics of mutualistic populations with open life histories.
British Dictionary definitions for mutualistic


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
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Word Origin and History for mutualistic

1885, from mutualist "advocate of mutualism" (1848); see mutualism.



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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mutualistic in Medicine

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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mutualistic 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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Encyclopedia Article for mutualistic


association between organisms of two different species in which each is benefited. Mutualistic arrangements are most likely to develop between organisms with widely differing living requirements. The partnership between nitrogen-fixing bacteria and leguminous plants is an example, as is the association between cows and rumen bacteria (the bacteria live in the digestive tract and help digest the plants eaten by the cow). The associations between tree roots and certain fungi are often mutualistic (see mycorrhiza.)

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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