Homosexuality is defined as being attracted to somebody of the same sex. The word, coined in 1869, comes from the Greek prefix "homo-," which means "same," and the Latin root "sex." The term "homosexual" can be used to describe somebody's romantic preference, sexual history or identity.
The terms "homosexuality" and "heterosexuality" were first developed when homosexuality was considered a psychological illness. The American Psychiatric Association of Mental Disorders defined it as a psychiatric ailment that could be "cured," in its official diagnostic manual. It wasn't until 1973 that this definition (and term) was removed from the manual. This was mainly due to the gay rights movement of the late 1960s to mid '70s. This movement aimed to achieve freedom from persecution and attain civil rights for all lesbian, gay, bisexual and transgender people.