scav·en·ger 
(skăvən-jər)
(skăvən-jər)n.
1. An animal, such as a vulture or housefly, that feeds on dead or decaying matter.
2. One that scavenges, as a person who searches through refuse for useful items.
3. Chemistry A substance added to a mixture to remove or inactivate impurities.
[Alteration of Middle English scauager, schavager, official charged with street maintenance, from Anglo-Norman scawager, toll collector, from scawage, a tax on the goods of foreign merchants, from Flemish scauwen, to look at, show.]