\Pen*den"tive\, n. [F. pendentif, fr. L. pendere to
hang.] (Arch.)
   (a) The portion of a vault by means of which the square
       space in the middle of a building is brought to an
       octagon or circle to receive a cupola.
   (b) The part of a groined vault which is supported by, and
       springs from, one pier or corbel.