impotency vs impotence

impotency and impotence both are nouns.

Word	Noun	Adjective	Verb	Adverb
impotency	Yes	No	No	No
impotence	Yes	No	No	No

As nouns, impotency and impotence are synonyms defined as:

impotency and impotence: the quality of lacking strength or power; being weak and feeble

Other synonyms of impotency include powerlessness.

As nouns, impotency and impotence are synonyms defined as:

impotency and impotence: an inability (usually of the male animal) to copulate

impotency (noun)	impotence (noun)
the quality of lacking strength or power; being weak and feeble	the quality of lacking strength or power; being weak and feeble
an inability (usually of the male animal) to copulate	an inability (usually of the male animal) to copulate