Lesbian, Gay, Bisexual, Transgender, and Queer LGBTQ Resources and Studies

In 1972, psychologist George Weinberg defined homophobia as, "the dread of being in close quarters with homosexuals," or, more generally, "revulsion toward homosexuals."  Today, homophobia is generally thought of as an unreasonable fear or hatred of homosexuality, especially in others but also in oneself (known as internalized homophobia).

from Completely Queer:  The Lesbian and Gay Encyclopedia

(Warning - this video may be disturbing to some viewers.  It is provided as a classic and extreme example of homophobia).