The word homosexual is a Greek and Latin hybrid with the first element derived from Greek ὁμός homos, 'same' (not related to the Latin homo, 'man', as in Homo sapiens), thus connoting sexual acts and affections between members of the same sex, including lesbianism. Gay generally refers to male homosexuality, but may be used in a broader sense to refer to all LGBT people. In the context of sexuality, lesbian refers only to female homosexuality. The word "lesbian" is derived from the name of the Greek island Lesbos, where the poet Sappho wrote largely about her emotional relationships with young women.
Many modern style guides in the U.S. recommend against using homosexual as a noun, instead using gay man or lesbian. Similarly, some recommend completely avoiding usage of homosexual as it has a negative, clinical history and because the word only refers to one's sexual behavior (as opposed to romantic feelings) and thus it has a negative connotation. Gay and lesbian are the most common alternatives. The first letters are frequently combined to create the initialism LGBT (sometimes written as GLBT), in which B and T refer to bisexual and transgender people.
The first known appearance of homosexual in print is found in an 1869 German pamphlet by the Austrian-born novelist Karl-Maria Kertbeny, published anonymously, arguing against a Prussian anti-sodomy law. In 1879, Gustav Jager used Kertbeny's terms in his book, Discovery of the Soul (1880). In 1886, Richard von Krafft-Ebing used the terms homosexual and heterosexual in his book Psychopathia Sexualis, probably borrowing them from Jager. Krafft-Ebing's book was so popular among both layman and doctors that the terms "heterosexual" and "homosexual" became the most widely accepted terms for sexual orientation.
Although early writers also used the adjective homosexual to refer to any single-sex context (such as an all-girls' school), today the term is used exclusively in reference to sexual attraction, activity, and orientation. The term homosocial is now used to describe single-sex contexts that are not specifically sexual. There is also a word referring to same-sex love, homophilia.
Homosexuality is romantic or sexual attraction or behavior between members of the same sex or gender. As a sexual orientation, homosexuality refers to "an enduring pattern of or disposition to experience sexual, affectional, or romantic attractions" primarily or exclusively to people of the same sex; "it also refers to an individual's sense of personal and social identity based on those attractions, behaviors expressing them, and membership in a community of others who share them."
Homosexuality is one of the three main categories of sexual orientation, along with bisexuality and heterosexuality, within the heterosexual-homosexual continuum (with asexuality sometimes considered the fourth). Scientific and medical understanding is that sexual orientation is not a choice, but rather a complex interplay of biological and environmental factors. Although some religious sects hold the view that homosexual activity is unnatural or dysfunctional. research shows that homosexuality is an example of normal variation in human sexuality and not a source of negative psychological effects. Prejudice and discrimination against homosexual and bisexual people, however, have been shown to cause psychological harm.
The most common terms for homosexual people are lesbian for women and gay for men, though gay is also used to refer generally to homosexual men and women. The number of people who identify as gay or lesbian—and the proportion of people who have same-sex sexual experiences—are difficult for researchers to estimate reliably for a variety of reasons. In the modern West, according to major studies, 2% to 13% of the population is homosexual or has had some form of same-sex sexual contact within his or her lifetime. In a 2006 study 20% of respondents anonymously reported some homosexual feelings, although fewer participants identified themselves as homosexual. Homosexual behavior is also widely observed in animals.
Many gay and lesbian people are in committed same-sex relationships, though only recently have census forms and political conditions facilitated their visibility and enumeration. These relationships are equivalent to heterosexual relationships in essential psychological respects. Homosexual relationships and acts have been admired, as well as condemned, throughout recorded history, depending on the form they took and the culture in which they occurred. Since the end of the 19th century, there has been a movement towards increased visibility, recognition and legal rights for homosexual people, including the rights to marriage and civil unions, adoption and parenting, employment, military service, and equal access to health care.