Antonyms of noun inability

2 senses of inability

Sense 1
inability -- (lack of ability (especially mental ability) to do something)
       Antonym of ability (Sense 2)
      => ability, power -- (possession of the qualities (especially mental qualities) required to do something or get something done; "danger heightened his powers of discrimination")

Sense 2
inability, unfitness -- (lacking the power to perform)
       Antonym of ability (Sense 1)
      => ability -- (the quality of being able to perform; a quality that permits or facilitates achievement or accomplishment)

Synonyms/Hypernyms (Ordered by Estimated Frequency) of noun inability

2 senses of inability

Sense 1
inability -- (lack of ability (especially mental ability) to do something)
       => cognition, knowledge, noesis -- (the psychological result of perception and learning and reasoning)

Sense 2
inability, unfitness -- (lacking the power to perform)
       => quality -- (an essential and distinguishing attribute of something or someone; "the quality of mercy is not strained"--Shakespeare)