originally "person hired to remove refuse from streets," from Middle English scawageour (late 14c.), London official in charge of collecting tax on goods sold by foreign merchants, from Anglo-French scawager, from scawage "toll or duty on goods offered for sale in one's precinct" (c.1400), from Old North French escauwage "inspection," from a Germanic source (cf. Old High German scouwon, Old English sceawian "to look at, inspect," see show (v.)). With intrusive -n- (c.1500) as in harbinger, passenger, messenger. Extended to animals 1590s. Scavenger hunt is attested from 1940.