Scum

n.	1.
	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. - Spenser.
	2.	refuse; recrement; anything vile or worthless. The great and innocent are insulted by the scum and refuse of the people. - Addison.
v. t.	1.	To take the scum from; to clear off the impure matter from the surface of; to skim. [imp. & p. p. Scummed ; p. pr. & vb. n. Scumming .] You that scum the molten lead. - Dryden & Lee.
	2.	To sweep or range over the surface of. Wandering up and down without certain seat, they lived by scumming those seas and shores as pirates. - Milton.
v. i.	1.	To form a scum; to become covered with scum. Also used figuratively. Life, and the interest of life, have stagnated and scummed over. - A. K. H. Boyd.

Noun	1.	scum - worthless people Synonyms: trash
	2.	scum - a film of impurities or vegetation that can form on the surface of a liquid

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