A friend with whom one enjoys several kinds of intimacy which are traditionally regarded outside the domain of platonic friendship, principally including that of an emotional and sexual nature. In this romantic partnership, certain boundaries, terms of commitment, and the expectation of exclusivity may be ambiguous. Therefore, to sustain an intimate friendship requires a diligent effort in using honest and deliberate communication. Also called an "IF".
My intimate friend (IF) and I talk about our feelings after we bang.

Fox and Dana are intimate friends; they maintain professional boundaries M-F and make love on weekends.
by Nathan Kelley September 30, 2019
A friend of the opposite sex, whom one mutually satisfies their sexual and social needs with, without commitment.
by new2thagame March 29, 2005