Each gains benefits from the other

• The relation between two different species of organisms that are interdependent

Wikipedia Word definitions in Wikipedia
Mutualism is the way two organisms of different species exist in a relationship in which each individual benefits from the activity of the other. Similar interactions within a species are known as co-operation . Mutualism can be contrasted with interspecific ...

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
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 .

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Mutualism \Mu"tu*al*ism\, n. (Ethics) The doctrine of mutual dependence as the condition of individual and social welfare. --F. Harrison. --H. Spencer. --Mallock.

Wiktionary Word definitions in Wiktionary
n. (context ecology English) any interaction between two species that benefits both; typically involves the exchange of substances or services

WordNet Word definitions in WordNet
n. the relation between two different species of organisms that are interdependent; each gains benefits from the other [syn: symbiosis ]