n. pl. incisors, incisores (-sorz, in-sī-sō′ rēz). In anatomy and zoology, an incisive or cutting tooth; a front tooth; any tooth of the upper jaw which is situated in the premaxillary or intermaxillary bone, or any corresponding tooth of the lower jaw.Same as incisorial: as, an incisor tooth.Of or pertaining to the incisor teeth: as, incisor nerves.