voicelessness vs impotency

voicelessness and impotency both are nouns.

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

As nouns, impotency is a hypernym of voicelessness; that is, impotency is a word with a broader meaning than voicelessness:

Other hypernyms of voicelessness include impotence, powerlessness.

voicelessness (noun)	impotency (noun)
having no voice in the management or control of affairs	the quality of lacking strength or power; being weak and feeble
speaking softly without vibration of the vocal cords	an inability (usually of the male animal) to copulate
(phonetics, of a consonant) The property of being spoken without vibration of the vocal cords, as [t], [s], or [f].
a disorder of the vocal organs that results in the loss of voice