a consistent inability to sustain an erection sufficient for sexual intercourse. Also commonaly known as impotence. Medically, the term erectile dysfunction is used to differentiate impotence from other problems that interfere with sexual intercourse (such as lack of sexual desire and problems with ejaculation and orgasm). Impotence usually has a physical cause, such as disease, injury, drug side-effects, or a disorder that impairs blood flow in the penis. Impotence is treatable in all age groups.