dross

noun

1. (uncountable, usually)Waste or impure matter.
2. (uncountable, usually)Waste or impure matter.
3. (uncountable, usually)Waste or impure matter.

   “Dross is related with the incomplete expulsion of the melt from the bottom of the kerf. For precision applications where the clean cutting edges are important the formation of dross at the bottom of the cutting kerf must be controlled. This requires deep understanding of the mechanisms of dross formation and the various materials and laser-cutting parameters which potentially control the formation of dross. For example, the highly cleaned (dross-free) cutting edges can be obtained in […]”

   “One of the main problems with recycling and melting magnesium is the presence of particles in the melt which lead to the formation of dross and sludge. To be more precise, the necessary removal of dross and sludge greatly increase the costs of the facility. And, material is lost.”

4. (figuratively, uncountable, usually)Worthless or trivial matter.

   “What thou lovest well remains, the rest is dross”

5. (slang, uncountable, usually)Residual raw opium left in an opium pipe which can be recycled for further sale or use.

verb

1. (transitive)To remove dross from.