Definitions for corundumkəˈrʌn dəm
Random House Webster's College Dictionary
a mineral, aluminum oxide, Al2O3, noted for its hardness: transparent varieties, as sapphire and ruby, are used as gems, other varieties as abrasives: often made synthetically.
Origin of corundum:
1720–30; < Tamil kuruntam; akin to Skt kuruvinda ruby
very hard mineral used as an abrasive
An extremely hard mineral, a form of aluminum oxide with the chemical formula AlO, that occurs in the form of the gemstones sapphire and ruby; it is used as an abrasive.
Origin: From குருந்தம்.
the earth alumina, as found native in a crystalline state, including sapphire, which is the fine blue variety; the oriental ruby, or red sapphire; the oriental amethyst, or purple sapphire; and adamantine spar, the hair-brown variety. It is the hardest substance found native, next to the diamond