(1):
(n.) That which moves or influences the mind, or operates on the passions; that which incites, or has a tendency to incite, to determination or action; that which prompts to good or ill; motive; spur; as, the love of money, and the desire of promotion, are two powerful incentives to action.
(2):
(a.) Serving to kindle or set on fire.
(3):
(a.) Inciting; encouraging or moving; rousing to action; stimulative.