The quality or state of being able; power to perform, whether physical, moral, intellectual, conventional, or legal; capacity; skill or competence in doing; sufficiency of strength, skill, resources, etc.; -- in the plural, faculty, talent.
Webster's Revised Unabridged Dictionary (1913), edited by Noah Porter. About
The natural equipment to accomplish some small part of the meaner ambitions distinguishing able men from dead ones. In the last analysis ability is commonly found to consist mainly in a high degree of solemnity. Perhaps, however, this impressive quality is rightly appraised; it is no easy task to be solemn.
The Devil's Dictionary, by Ambrose Bierce, 1911 (About)
Noun 1. the quality of being able to perform; a quality that permits or facilitates achievement or accomplishment (antonym) inability, unfitness (hypernym) quality (hyponym) adaptability (attribute) able 2. possession of the qualities (especially mental qualities) required to do something or get something done; "danger heightened his powers of discrimination" (synonym) power (antonym) inability (hypernym) cognition, knowledge, noesis (hyponym) know-how (attribute) able