late 14c., "shaving of the head or part of it," especially as a religious rite, from Anglo-French tonsure (mid-14c.), Old French tonsure "ecclesiastical tonsure; sheep-shearing" (14c.), from Latin tonsura "a shearing, clipping," from tonsus, past participle of tondere "to shear, shave, clip, crop," from PIE *tend-, from root *tem- "to cut" (see tome). The verb is attested from 1706 (implied in tonsured). Related: Tonsuring.