alum

3 definitions found

alum - Collaborative International Dictionary of English v.0.48 :

  Alum \Al"um\, n. [OE. alum, alom, OF. alum, F. alun, fr. L.
     alumen alum.] (Chem.)
     A double sulphate formed of aluminium and some other element
     (esp. an alkali metal) or of aluminium. It has twenty-four
     molecules of water of crystallization.
     [1913 Webster]
  
     Note: Common alum is the double sulphate of aluminium and
           potassium. It is white, transparent, very astringent,
           and crystallizes easily in octahedrons. The term is
           extended so as to include other double sulphates
           similar to alum in formula.
           [1913 Webster]

  Alum \Al"um\, v. t.
     To steep in, or otherwise impregnate with, a solution of
     alum; to treat with alum. --Ure.
     [1913 Webster]

alum - WordNet (r) 2.1 (2005) :

  alum
      n 1: a white crystalline double sulfate of aluminum: the
           ammonium double sulfate of aluminum [syn: alum, ammonia alum
           , ammonium alum]
      2: a white crystalline double sulfate of aluminum: the potassium
         double sulfate of aluminum [syn: alum, potassium alum,
         potash alum]
      3: a person who has received a degree from a school (high school
         or college or university) [syn: alumnus, alumna, alum,
         graduate, grad]
      4: a double sulphate of aluminum and potassium that is used as
         an astringent (among other things)