Impotent means that the man can’t complete sexual intercourse as he can’t get an erection. Impotence among young men usually has psychological causes.
Worry about how they will ‘perform’, fear of infection or fear of an unwanted pregnancy might stop the man getting an erection. A lot of older men become impotent due to physical reasons, such as clogged blood vessels, being overweight or diabetes. Men who are impotent due to sickness can be treated with medicines such as Viagra.