from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An extremely hard mineral, aluminum oxide, Al2O3, sometimes containing iron, magnesia, or silica, that occurs in gem varieties such as ruby and sapphire and in a common black, brown, or blue form used chiefly in abrasives.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An extremely hard mineral, a form of aluminum oxide with the chemical formula Al2O3, that occurs in the form of the gemstones sapphire and ruby; it is used as an abrasive.
from the GNU version of the Collaborative International Dictionary of English
- n. 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.
from The Century Dictionary and Cyclopedia
- n. Alumina, or the oxid of the metal aluminium, as found native in a crystalline state.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. very hard mineral used as an abrasive
Tamil kuruntam.(American Heritage® Dictionary of the English Language, Fourth Edition)
From Tamil குருந்தம் (kuruntam, "ruby"). (Wiktionary)