part of derives from/develops from tooth 1: One of the hard bony appendages that are borne on the jaws or in many of the lower vertebrates on other bones in the walls of the mouth or pharynx and serve especially for the prehension and mastication of food and as weapons of offense and defense. 2: Any of various usually hard and sharp processes especially about the mouth of an invertebrate. BTO:0000397 BrendaTissueOBO mouth enamel organ