n. One who abets or incites; one who aids or encourages another to commit a crime; a supporter or encourager of something bad. Abettor is the form used in law.n. In law, an abettor, as distinguished from an accessory, is more especially one who, being present, gives aid or encouragement.n. One who aids, supports, or encourages: in a good sense.n. Synonyms Abettor, Accessory, Accomplice. See accomplice.