scavenger
/ˈskævɪndʒə(r)/noun
1- an animal that feeds on carrion, dead plant material, or refuse食腐动物
1.1
- a person who searches for and collects discarded items捡破烂的人。
1.2
- Brit. archaic a person employed to clean the streets〈英, 古〉清扫工, 清道夫。
1.3
- Chemistry a substance that reacts with and removes particular molecules, radicals, etc.【化】（通过化合作用的）清除剂; 净化剂。
词源
mid 16th cent.: alteration of earlier scavager, from Anglo-Norman French scawager, from Old Northern French escauwer 'inspect', from Flemish scauwen 'to show'. The term originally denoted an officer who collected scavage, a toll on foreign merchants' goods offered for sale in a town, later a person who kept the streets clean.