1710s, "that which disqualifies;" 1770, "act of disqualifying; state of being disqualified;" noun of action or state from disqualify.

"act of incapacitating, state of being incapacitated; act of disqualifying; disqualification," 1741, noun of action from incapacitate.

mid-15c., inhabilite, "disqualification for office," from in- (1) + ability. Earlier was unability "incapability; incompetence" (late 14c.). General sense "state of being unable" is recorded by c. 1500.