Define impulsive. impulsive synonyms, impulsive pronunciation, impulsive translation, English dictionary definition of impulsive. adj. 1. Inclined to act on impulse rather than thought . IMPULSIVE definition: 1. showing behaviour in which you do things suddenly without any planning and without considering…. Learn more. The meaning of IMPULSIVE is arising from an impulse. How to use impulsive in a sentence. Synonym Discussion of Impulsive . ‘Impulsive’ refers to behavior or decisions that are made suddenly and without careful thought . It often reflects spontaneity or acting based on immediate feelings rather than logic or planning.