To support, or prevent from falling, by placing something under or against; as, to prop up a fence or an old building; to sustain; to maintain; as, to prop a declining state. Till the bright mountains prop the incumbent sky. (pope) For being not propp'd by ancestry. (Shak) I prop myself upon those few supports that are left me. (Pope)
Origin: 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, Propagate.