Co-rūn'dum, n.

n. [Also corindon. From Hind. kurand, corundum stone.] (Min.) 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 known substance next to the diamond. Dana.

☞ The name corundum is sometimes restricted to the non-transparent or coarser kinds. Emery is a dark-colored granular variety.