by 1908, originally "fear of humans," ultimately from Latin homo "man, male human; human being" + phobia + -ic.

[H]e imported a whole boxcar of broncos from the West, homophobic mustangs, as it turned out, that nobody but a rodeo hand could have ridden. [F. Reid Buckley, Life Magazine, 1970]

The "fear of homosexuals" sense is attested by 1969, from homo- (2) "homosexual" + -phobia + -ic. Even early on the term was used with a tinge of "unreasonable or abusive fear of homosexuals" and in current use it typically implies or asserts an active hatred. Related: Homophobe; homophobia