Corundum

• POS: Noun
• HYPHEN: co=run=dum

CIDE DICTIONARY

Corundum, n. [From Hind. kurand corundum stone.].

 The mineral alumina (Al2O3), as found native in a crystalline state. Transparent varieties are used as gemstones, 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.  [1913 Webster]
" The name corundum is sometimes restricted to the non-transparent or coarser kinds. Emery is a dark-colored granular variety, usually admixed with magnetic iron ore."  [1913 Webster]

OXFORD DICTIONARY

Corundum, n. Mineral. extremely hard crystallized alumina, used esp. as an abrasive, and varieties of which, e.g. ruby and sapphire, are used for gemstones.

Etymology

Tamil kurundam f. Skr. kuruvinda ruby