. Ability to cause or prevent an action, make things happen; the discretion to act or not act. Opposite of disability, it differs from a right in that it has no accompanying duties.
2. Law: (1) An instrument transferring or vesting legal authorization.
(2) The ability conferred on a person by law to determine and alter (by his or her own will) the rights, duties, liabilities, and other legal relations, of himself or others.