dross

Dross has been a part of the English language since Anglo-Saxon times. It comes from the Old English word drōs, meaning "dregs," those solid materials that fall to the bottom of a container full of a liquid such as coffee or wine. While dross today is used to refer to anything of low value or quality, its earliest use is technical: dross is a metallurgy term referring to solid scum that forms on the surface of a metal when it is molten or melting—remove the dross to improve the metal. The metallurgical sense of the word is often hinted at in its general use, with dross set in contrast to gold, as when 19th century British poet Christina Rossetti wrote "Besides, those days were golden days, / Whilst these are days of dross."