Alumina

2 definitions found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Alumina \A*lu"mi*na\, n. [L. alumen, aluminis. See {Alum}.]
     (Chem.)
     One of the earths, consisting of two parts of aluminium and
     three of oxygen, {Al2O3}.
     [1913 Webster]
  


     Note: It is the oxide of the metal aluminium, the base of
           aluminous salts, a constituent of a large part of the
           earthy siliceous minerals, as the feldspars, micas,
           scapolites, etc., and the characterizing ingredient of
           common clay, in which it exists as an impure silicate
           with water, resulting from the decomposition of other
           aluminous minerals. In its natural state, it is the
           mineral corundum.
           [1913 Webster]

From WordNet (r) 2.0 [wn]:

  alumina
       n : any of various forms of aluminum oxide occurring naturally
           as corundum [syn: {aluminum oxide}, {aluminium oxide}]