Erectile dysfunction, also known as impotence or male sexual dysfunction, is an inability to get an erection that is good enough to achieve intercourse in a satisfactory way for both partners. The severity of erectile dysfunction can vary from complete lack of erection, to a partial erection that is not enough to penetrate your partner or is lost soon after you penetrate. Although erectile dysfunction is typically more common among older men, it can occur at any age and often does 4 (Thompson et al. 2005. JAMA).