corundum

Definitions of corundum
  1. noun
    very hard mineral used as an abrasive
    synonyms: corundom
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    alumina, aluminium oxide, aluminum oxide
    any of various forms of aluminum oxide occurring naturally as corundum
    ruby
    a transparent deep red variety of corundum; used as a gemstone and in lasers
    sapphire
    a precious transparent stone of rich blue corundum valued as a gemstone
    alundum
    a substance made of fused alumina
    star sapphire
    a sapphire that when cut shows a starlike figure in reflected light because of its crystalline structure
    type of:
    mineral
    solid homogeneous inorganic substances occurring in nature having a definite chemical composition
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