"support," 1440, from M.Du. proppe "vine prop, support," of unknown origin. Related to O.H.G. pfropfo, Ger. pfropfen "to prop," perhaps from L. propago "a set, layer of a plant" (see propagation). Ir. propa, Gael. prop are from English. The verb meaning "to support" is attested from 1492.
"object used in a play," 1911, from props (1841), shortened form of properties (in theatrical use from early 15c.). Props as slang shortening for proper respects (or something similar) appeared c.1999.