Every distinct wording since 2010, newest first.
July 12, 2019 · Core Set 2020
An ability can be a characteristic an object has that lets it affect the game. An object’s abilities are defined by its rules text or by the effect that created it. Abilities can also be granted to objects by rules or effects. (Effects that grant abilities usually use the words “has,” “have,” “gains,” or “gain.”) Abilities generate effects. (See rule 609, “Effects.”)
February 1, 2010 · Worldwake
An instant or sorcery spell is targeted if its spell ability identifies something it will affect by using the phrase "target [something]," where the "something" is a phrase that describes an object, player, or zone. The target(s) are chosen as the spell is cast; see rule 601.2c. (If an activated or triggered ability of an instant or sorcery uses the word target, that ability is targeted, but the spell is not.)