one of the sharp teeth at the front of the mouth that are used for biting. Humans have eight incisors. compare canine, molar, premolar, wisdom toothTopics Bodyc2切牙;门齿 Word Originlate 17th cent.: from medieval Latin, literally ‘cutter’, from Latin incis- ‘cut into, engraved’, from the verb incidere, from in- ‘into’ + caedere ‘to cut’.