Abrasive

An abrasive is something that is very hard. It is also rough. It is used to rub things so they get smooth. When abrasives are glued to paper, it makes sandpaper. Aluminium oxide is a common abrasive. Abrasives are used to make the ends of wood pieces smooth and to smooth the cut ends of metal. The hardest natural abrasive is diamond. Diamond is commonly used in saw blades designed to cut tile or stone.

Abrasive Media

Grit size ranging from 2 mm (the large grain) (about F 10 using FEPA standards) to about 40 micrometres (about F 240 or P 360).
A syringe with diamond powder, grade 14,000 mesh, mixed with a liquid to be used for polishing very hard surfaces.
Assorted grinding wheels as examples of bonded abrasives.
A grinding wheel with a reservoir to hold water as a lubricant and coolant.
A German Klingspor sandpaper showing its backing and FEPA grit size.
Here the abrasiveness of toothpaste is detailed by its Relative Dentin Abrasivity (RDA)

This short article about science can be made longer. You can help Wikipedia by adding to it.