corundum kuh ruhn duhm n very hard mineral used as an abrasive Usage(s) Dov Gruner, 33, a Jew with a bullet-crushed jaw and the corundum-hard eyes of an Irgun Zvai Leumi triggerman, stood before a Jerusalem Military Court. Founded in 1902 to mine corundum for use in abrasive wheels, 3M struggled into the manufacture of sandpaper and then into masking tape. Acheson called the stuff "carborundum," because he thought it was composed of corundum and carbon before it was analyzed as silicon carbide. Synonym(s) corundom