the inability of a person to experience sexual arousal or to achieve sexual satisfaction under appropriate circumstances, as a result of either physical disorder or, more commonly, psychological problems. The most common forms of sexual dysfunction have traditionally been classified as impotence (inability of a man to achieve or maintain penile erection) and frigidity (inability of a woman to achieve arousal or orgasm during sexual intercourse). Because these terms—impotence and frigidity—have developed pejorative and misleading connotations, they are no longer used as scientific classifications, having been superseded by more specific terms; however, both terms remain in common usage, with a variety of meanings and associations (see frigidity; impotence).

Sexual dysfunctions recognized by professional therapists include hyposexuality (or inhibited sexual excitement), in which sexual arousal can be achieved only with great difficulty; anorgasmia, in which a woman has a recurrent and persistent inability to achieve orgasm despite normal sexual stimulation; vaginismus, in which the woman's vaginal muscles contract strongly during intercourse, making coitus difficult or impossible; dyspareunia, in which a woman experiences significant pain during attempts at intercourse; erectile impotence, in which a man cannot sustain an erection; ejaculatory impotence (or inhibited male orgasm), in which a man cannot achieve orgasm in the woman's vagina, although he can sustain an erection and may reach orgasm by other methods; and premature ejaculation, in which the man ejaculates before or immediately after entering the vagina.

In most cases, each of these dysfunctions reflects the individual's anxiety or other negative feelings about the sex act or partner, although emotional conflicts outside the sexual relationship itself can also produce failures of sexual function. Appropriate sex therapy, designed to help the individual relax in his or her sexual role, can often overcome the anxiety and eliminate the dysfunction, although the success of such therapy varies markedly among the various dysfunctions and among individual patients. When a specific physical condition predisposes to the dysfunction, it must be treated medically; alcoholism and endocrine or neurological disorders are among the common physical causes of sexual dysfunction. Sexual dysfunctions that are secondary to more severe psychological or personality disorders may require specific psychotherapy.