A term preferred by some writers in preference to using "homosexual
" as a noun.
In a newsmagazine cover article on Gore Vidal in the late 1970s, the celebrated author and essayist explained that, since "homosexual" is used as an adjective ("homosexual fantasy"), the noun form needed something more, well, distinctive and substantive: he used "homosexualist
" to describe someone who is gay in practice, or as a state of being.
One doesn't argue lightly with Gore Vidal but there are precedents either way in forming nouns. "Alcoholic drink" / "Joe's an alcoholic," uses "alcoholic" first as an adjective, then as a noun. Similarly, "Green politics" / "Cary has become a Green."
OTOH a medical practitioner of psychiatry is not a "psychiatric" (better used as an adjective = "psychiatric evaluation"), but a "psychiatrist," a description of a person, not a field. One who enjoys sensual things is a "sensualist" but has an appreciation of the sensual.