Mutualism
Etymology
From Latin mutuus, "reciprocal, done in exchange" (related to mutare, "to change"), via the -ism suffix. The naturalist Pierre-Joseph van Beneden popularized the biological term in the 1870s for partnerships of shared benefit, such as bees and the flowers they pollinate. The word had already carried a social sense of cooperation for mutual aid.
noun · /MYOO-choo-uh-liz-um/
A relationship between two different organisms in which both come out ahead.
What it names
The genuinely win-win arrangement, where each party helps the other precisely because doing so also helps itself.
Example
Their carpool was pure mutualism: she hated driving, he hated paying for parking, and both got exactly what they wanted.
Related idea
Symbiosis is the general fact of living closely together; mutualism is the happy subtype where the ledger comes out positive for both.
See also