scum
1. scum \'sk*m\ \'sk*m-e-\ n [ME, fr. MD schum; akin to OHG scu-m foam] 1a: extraneous matter or impurities risen to or formed on the surface of a liquid often with a foul filmy covering 1b: the scoria of metals in a molten state : DROSS 2a: REFUSE 2b: the lowest class : RABBLE - scum.my aj 2. scum vi or scummed; or scum.ming : to become covered with or as if with scum