Scum | Webster's Dictionary (1865)

Scŭm, n.

noun

n. [Dan. & Sw. skum, Icel. skŭm, L. Ger. schum, D. schuim, O. H. Ger. scŭm, N. H. Ger. schaum, Gael. sgŭm, O. Fr. escume, N. Fr. écume, Pr., Sp., & Pg. escuma, It. *schiuma.]

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.
Hence, refuse; recrement; that which is vile or worthless.

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

Scŭm, v. i.

verbintransitive

v. i. To form a scum; to become covered with scum.

Life and the interest of life have stagnated and scummed over. A. K. H. Boyd.

Scŭm, v. t.

verbtransitive

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. “You that scum the molten lead.” Dryden. 2. To sweep over; to scour; to range. [Obs.] Wandering up and down without certain seat, they lived by scumming these seas and shores as pirates. Milton.