Ton"sure (?), n. [F., fr. L. tonsura a shearing, clipping, from tondere, tonsum, to shear, shave; cf. Gr. to gnaw; perhaps akin to Gr. to cut, and E. tome.]
The act of clipping the hair, or of shaving the crown of the head; also, the state of being shorn.
2. R. C. Ch. (a)
The first ceremony used for devoting a person to the service of God and the church; the first degree of the clericate, given by a bishop, abbot, or cardinal priest, consisting in cutting off the hair from a circular space at the back of the head, with prayers and benedictions; hence, entrance or admission into minor orders.
The shaven corona, or crown, which priests wear as a mark of their order and of their rank.
© Webster 1913.