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1.                 From The Collaborative International Dictionary of English v.0.48:
                   
   
   
                   
                     
   gum tree \gum" tree`\ n.
      Any tree that exudes a gum, such as:
      (a) The black gum (Nyssa multiflora), one of the largest
          trees of the Southern States, bearing a small blue fruit,
          the favorite food of the opossum. Most of the large trees
          become hollow.
      (b) A tree of the genus Eucalyptus; a eucalypt. See
          Eucalpytus.
      (c) The sweet gum tree of the United States (Liquidambar
    styraciflua), a large and beautiful tree with pointedly
          lobed leaves and woody burlike fruit. It exudes an
          aromatic terebinthine juice.
      (d) The sour gum tree.
          [1913 Webster]