symbiosis

sym·bi·o·sis

noun \ˌsim-ˌbī-ˈō-səs, -bē-\

plural sym·bi·o·ses \-ˌsēz\

Definition of SYMBIOSIS

1

: the living together of two dissimilar organisms in more or less intimate association or close union

2

: the intimate living together of two dissimilar organisms in a mutually beneficial relationship; especially : mutualism