1.  dross(n = noun.substance) impurity - worthless or dangerous material that should be removed; "there were impurities in the water"
is a kind of waste, waste material, waste matter, waste product

2.  dross(n = noun.substance) scoria, slag - the scum formed by oxidation at the surface of molten metals;
is a kind of scum
has particulars: basic slag

dross, n.
1 rubbish, refuse.
2 a the scum separated from metals in melting. b foreign matter mixed with anything; impurities.

Derivative:
drossy adj.

Etymology:
OE dros: cf. MLG drosem, OHG truosana

N  uncleanness, impurity, immundity, immundicity, impurity, defilement, contamination, defoedation, soilure, soiliness, abomination, leaven, taint, tainture, fetor, decay, putrescence, putrefaction, corruption, mold, must, mildew, dry rot, mucor, rubigo, slovenry, slovenliness, squalor, dowdy, drab, slut, malkin, slattern, sloven, slammerkin, slammock, slummock, scrub, draggle-tail, mudlark, dust-man, sweep, beast, dirt, filth, soil, slop, dust, cobweb, flue, smoke, soot, smudge, smut, grit, grime, raff, sossle, sozzle, sordes, dregs, grounds, lees, argol, sediment, settlement heeltap, dross, drossiness, mother, precipitate, scoriae, ashes, cinders, recrement, slag, scum, froth, hogwash, ditchwater, dishwater, bilgewater, rinsings, cheeseparings, sweepings, offscourings, outscourings, off scum, caput mortuum, residuum, sprue, fecula, clinker, draff, scurf, scurfiness, exuviae, morphea, fur, furfur, dandruff, tartar, riffraff, vermin, louse, flea, bug, chinch, mud, mire, quagmire, alluvium, silt, sludge, slime, slush, slosh, sposh, spawn, offal, gurry, lientery, garbage, carrion, excreta, slough, peccant humor, pus, matter, suppuration, lienteria, faeces, feces, excrement, ordure, dung, crap, shit, sewage, sewerage, muck, coprolite, guano, manure, compost, dunghill, colluvies, mixen, midden, bog, laystall, sink, privy, jakes, toilet, john, head, cess, cesspool, sump, sough, cloaca, latrines, drain, sewer, common sewer, Cloacina, dust hole, sty, pigsty, lair, den, Augean stable, sink of corruption, slum, rookery, dirty, filthy, grimy, unclean, impure, soiled, not to be handled with kid gloves, dusty, snuffy, smutty, sooty, smoky, thick, turbid, dreggy, slimy, mussy, slovenly, untidy, messy, uncleanly, unkempt, sluttish, dowdy, draggle-tailed, uncombed, unscoured, unswept, unwiped, unwashed, unstrained, unpurified, squalid, lutose, slammocky, slummocky, sozzly, nasty, coarse, foul, offensive, abominable, beastly, reeky, reechy, fetid, decayed, moldy, musty, mildewed, rusty, moth-eaten, mucid, rancid, weak, bad, gone bad, etercoral, lentiginous, touched, fusty, effete, reasty, rotten, corrupt, tainted, high, flyblown, maggoty, putrid, putrefactive, putrescent, putrefied, saprogenic, saprogenous, purulent, carious, peccant, fecal, feculent, stercoraceous, excrementitious, scurfy, scurvy, impetiginous, gory, bloody, rotting, rotten as a pear, rotten as cheese, crapulous, gross, fimetarious, fimicolous, they that touch pitch will be defiled.