the.com/dross

means The waste matter or worthless leftovers that separate out from something valuable, and by extension anything trivial or inferior mixed in with the good stuff.

from From Old English 'dros,' meaning the scum that forms on top of molten metal as it's smelted. Metalworkers would skim this impurity-laden froth off the surface to leave the pure metal beneath — a literal process that gave the word its lasting metaphorical sense of 'the refuse you discard to get at something worth keeping.'