\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.]
1. 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.
   (b) The shaven corona, or crown, which priests wear as a
       mark of their order and of their rank.