Sexual perversions are conditions in which sexual excitement or orgasm is associated with acts or imagery that are considered unusual within the culture. To avoid problems associated with the stigmatization of labels, the neutral term "paraphilia," derived from Greek roots meaning "alongside of" and "love," is used to describe what used to be called sexual perversions. A paraphilia is a condition in which a person's sexual arousal and gratification depend on a fantasy theme of an unusual situation or object that becomes the principal focus of sexual behavior.

Paraphilias can revolve around a particular sexual object or a particular act. They are defined by DSM-IV as "sexual impulse disorders characterized by intensely arousing, recurrent sexual fantasies, urges and behaviors considered deviant with respect to cultural norms and that produce clinically significant distress or impairment in social, occupational or other important areas of psychosocial functioning." The nature...