'Impotency' definitions:

Definition of 'impotency'

noun

The quality of lacking strength or power; being weak and feeble [syn: powerlessness, impotence, impotency] [ant: power, powerfulness]

noun

An inability (usually of the male animal) to copulate [syn: impotence, impotency] [ant: potence, potency]

From: GCIDE

Impotence \Im"po*tence\, Impotency \Im"po*ten*cy\, n. [L. impotenia inability, poverty, lack of moderation. See Impotent.]
1. The quality or condition of being impotent; lack of strength or power, animal, intellectual, or moral; weakness; feebleness; inability; imbecility. [1913 Webster]
Some were poor by impotency of nature; as young fatherless children, old decrepit persons, idiots, and cripples. --Hayward. [1913 Webster]
O, impotence of mind in body strong! --Milton. [1913 Webster]
2. Lack of self-restraint or self-control. [R.] --Milton. [1913 Webster]
3. (Law & Med.) Lack of procreative power; inability to copulate, or beget children; also, sometimes, sterility; barrenness; specifically, in males: the inability to achieve or sustain a penile erection; erectile dysfunction. [1913 Webster +PJC]