- The definition of commensalism is a relationship between two organisms where one is helped and the other is unaffected.
An example of commensalism is when a bird lives in a tree; the bird is helped by living in the tree because it has a place to build its nest and it is high up so protected from predators, but the tree is not affected.
A bird nesting in a tree is an example of commensalism.
- (biology) A sharing of the same environment by two organisms where one species benefits and the other is unaffected. An example is barnacles on whales.
- The act of eating together; table fellowship.
commensal + -ism