'Scum' definitions:

Definition of 'scum'

noun

Worthless people [syn: trash, scum]

noun

A film of impurities or vegetation that can form on the surface of a liquid

verb

Remove the scum from

From: GCIDE

Scum \Scum\, v. t. [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. [1913 Webster]
You that scum the molten lead. --Dryden & Lee. [1913 Webster]
2. To sweep or range over the surface of. [Obs.] [1913 Webster]
Wandering up and down without certain seat, they lived by scumming those seas and shores as pirates. --Milton. [1913 Webster]

From: GCIDE

Scum \Scum\, v. i. To form a scum; to become covered with scum. Also used figuratively. [1913 Webster]
Life, and the interest of life, have stagnated and scummed over. --A. K. H. Boyd. [1913 Webster]

From: GCIDE

Scum \Scum\ (sk[u^]m), n. [Of Scand. origin; cf. Dan. & Sw. skum, Icel. sk[=u]m, LG. schum, D. schuim, OHG. sc[=u]m, G. schaum; probably from a root meaning, to cover. [root]158. Cf. Hide skin, Meerschaum, Skim, v., Sky.] [1913 Webster]
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. [1913 Webster]
Some to remove the scum as it did rise. --Spenser. [1913 Webster]
2. refuse; recrement; anything vile or worthless. [1913 Webster]
The great and innocent are insulted by the scum and refuse of the people. --Addison. [1913 Webster]