Alum

3 definitions found

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

  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]

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

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

From WordNet (r) 2.0 [wn]:

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