Meaning of corundum

co•run•dum

Pronunciation: (ku-run'dum), [key]
— n.
  1. a common mineral, aluminum oxide, AlO, notable for its hardness: transparent varieties, as sapphire and ruby, are used as gems, other varieties as abrasives: often made synthetically.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.
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