Scum /(skŭm)/

1. The extraneous matter or impurities which rise to the surface of liquids in boiling or fermentation, or which form on the surface by other means; also, the scoria of metals in a molten state; dross.

   Some to remove the scum as it did rise.

2. refuse; recrement; anything vile or worthless.

   The great and innocent are insulted by the scum and refuse of the people.

imp. & p. p. Scummed; p. pr. & vb. n. Scumming

1. To take the scum from; to clear off the impure matter from the surface of; to skim.

   You that scum the molten lead.

2. To sweep or range over the surface of. [Obs.]

   Wandering up and down without certain seat, they lived by scumming those seas and shores as pirates.

1. To form a scum; to become covered with scum. Also used figuratively.

   Life, and the interest of life, have stagnated and scummed over.