The Collaborative International Dictionary of English v.0.48:
Prop \Prop\, v. t. [imp. & p. p. Propped; p. pr. & vb. n.
Propping.] [Akin to LG. & D. proppen to cram, stuff, thrust
into, stop, G. pfropfen, Dan. proppe, Sw. proppa; of
uncertain origin, cf. G. pfropfen to graft, fr. L. propago
set, layer of a plant, slip, shoot. Cf. 3d. Prop,
To support, or prevent from falling, by placing something
under or against; as, to prop up a fence or an old building;
(Fig.) to sustain; to maintain; as, to prop a declining
Till the bright mountains prop the incumbent sky.
For being not propp'd by ancestry. --Shak.
I prop myself upon those few supports that are left me.