Calotte \Ca*lotte"\, Callot \Cal"lot\, n. [F. calotte, dim. of cale a sort of flat cap. Cf. Caul.]

A close cap without visor or brim. Especially:
   (a) Such a cap, worn by English serjeants at law.
   (b) Such a cap, worn by the French cavalry under their helmets.
   (c) Such a cap, worn by the clergy of the Roman Catholic Church.

To assume the calotte, to become a priest.

Source: Webster's Revised Unabridged Dictionary (1913)