Old English ðorp "village, hamlet, farm, estate," reinforced by Old Norse ðorp, both from Proto-Germanic *thurpa- (source also of Old Frisian thorp, Frisian terp, Middle Dutch, Dutch dorp, German dorf "village," Gothic þaurp "estate, land, field"), probably from PIE root *treb- "dwelling" (see tavern). Preserved in place names ending in -thorp, -thrup.

"body of soldiers who are dropped by parachute into enemy territory," 1940, from parachute + plural of troop (n.).

1630s, "soldier in a cavalry troop," from troop (n.) + -er (1). Extended to "mounted policeman" (1858, in Australia) then to "state policeman" (U.S.) by 1911.

1825, "company, band," especially of performers, actors, dancers, etc., from French troupe "company" (see troop (n.)).