Surgery. a cone-shaped trephine designed to avoid penetration of the brain when incising the skull.
Origin: 1690–1700; < Gk (trýpanon) abáptiston (trepan) not dipped, neut. of abáptistos, equiv. to a-a-6+ baptis-, var. s. of baptízein to immerse (see baptize) + -tos verbal adj. suffix
[ab-ap-tis-tuh
n] 