1650s, probably an alteration of rouse. Related: Rousted; rousting.
Raid or harassment: What's the roust? You gonna close this place?
verb[1970s+; fr rouster or rooster, ''a deckhand or waterfront laborer,'' attested fr the mid1800s, hence with connotations of roughness; related to roustabout, fr British dialect rous-about, ''unwieldy,'' rousing, ''rough, shaggy,'' and rousy, ''filthy''; the semantic core seems to combine roughness with laziness, in the old heroic mold, and to be associated with the behavior of the rooster, who combines rough vigor with long periods on the perch; first verb sense found in 1904 prison slang in the sense ''to jostle,'' and by the 1940s in the sense ''to jostle so as to pick a pocket'']