IPA: /ɪmˈpoʊtənsi/
KK: /ɪmˈpoʊtənsi/
A condition in which a person is unable to achieve or maintain an erection, often associated with physical or psychological issues.
The doctor discussed the possible treatments for his impotency.
Impotency is formed from "im-" (meaning not) and "potentia" (from Latin, meaning power or ability). The word describes a state of lacking power or ability, particularly in a physical or functional sense.
Think of 'not' ('im-') having 'power' ('potentia') — that's why impotency means lacking power or ability.