A sexual dysfunction characterized by persistent or recurrent inability to attain or maintain an adequate erection of the penis until completion of sexual activity, believed to affect approximately 10 per cent of adult males, causing significant distress or problems of interpersonal interaction. It is not diagnosed if it is attributable to a drug or a general medical condition. Also called erectile dysfunction (ED), erectile impotence, or impotence. See also cyclic GMP, de-reflection, impotence (2), Viagra. Compare male orgasmic disorder.