Monosexual

Monosexuality is an umbrella term for anyone whose sexual orientation involves attraction to one gender only. It can include individuals who are gay, lesbian, straight, etc. It is the opposite of multisexual or bisexual.

Etymology
By 1922, the term "monosexual" was used by psychoanalysts and elaborated upon by Wilhelm Stekel, a contemporary follower of Sigmund Freud. Stekel believed that everyone was born "bisexual," which Freud and Stekel used to mean possessing male and female psychological traits. To Stekel, people only behaved as if they were monosexual&mdash;purely homosexual or purely heterosexual&mdash;but no one was monosexual in actuality. Everyone repressed either their heterosexual or homosexual tendencies during puberty, and anyone who seemed monosexual had repressed their bisexual nature to an extreme. Stekel framed a "normal person" as a heterosexual who became a healthy adult by suppressing their homosexual tendencies without becoming neurotic, while all homosexual people were neurotic and needed to stop repressing their heterosexual tendencies.

The bisexual community (in the sense of sexual orientation) was using the term by 1991 to mean non-bisexual people; however, the anthology Bi Any Other Name stated that the term was created by the bisexual movement.