Pendentive \Pen*den"tive\ (p[e^]n*d[e^]nt"[i^]v), 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.
[1913 Webster]