A same-sex relationship is a relationship between two persons of the same sex and can take many forms, from romantic and sexual, to non-romantic homosocially-close relationships. The term is primarily associated with homosexual couples. Same-sex marriage refers to the institutionalized recognition of such couples. The term same-sex relationship is not strictly related to the sexual orientation of the participants. As people in the bisexual-polysexual-pansexual, queer, asexual and also heterosexual spectra may participate in same-sex relationships (particularly depending on the legal, social and scientific definition of sex, that often erases the birth gender assignment-diverging identities of binary and genderqueer/non-binary trans people and those of ethnic genders alike), some activists claim that referring to a same-sex relationship as a “gay relationship” or a “lesbian relationship” is a form of bisexual erasure.