means A creature or person who feeds on or collects discarded, decaying, or leftover things that others have abandoned.

from From the Anglo-Norman 'scawage' (or 'scavage'), a medieval toll levied on goods offered for sale by foreign merchants. The official who collected it was a 'scavager' — and his duties later expanded to keeping the streets clean. The intrusive 'n' crept in over time (the same way 'messenger' grew from 'message' and 'passenger' from 'passage'), and the word drifted from tax collector to street cleaner to anything that lives off others' leavings.