The Collaborative International Dictionary of English v.0.48:

mammee apple \mammee apple\ n. (Bot.)
   A tropical American tree (Mammea americana) having edible
   fruit (the mammee apple) with a leathery rind.

   Syn: mammee, mamey, mammee tree, Mammea americana.
        [WordNet 1.5]

   2. The globular or ovoid tropical fruit of the mammee tree
      (Mammea americana), having a thick russet leathery rind
      and juicy yellow or reddish flesh.
      [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Mammee \Mam*mee"\, Mammee tree \Mam*mee" tree`\, n. [Haitian
   mamey.] (Bot.)
   A fruit tree of tropical America, belonging to the genus
   Mammea (Mammea Americana); also, its fruit, called the
   mammee apple. The latter is large, covered with a thick,
   tough ring, and contains a bright yellow pulp of a pleasant
   taste and fragrant scent. It is often called mammee apple.

   Syn: mammee apple, mammee, mamey, Mammea americana.
        [1913 Webster]

WordNet (r) 3.0 (2006):

mammee apple
    n 1: tropical American tree having edible fruit with a leathery
         rind [syn: mammee apple, mammee, mamey, mammee
         tree, Mammea americana]
    2: globular or ovoid tropical fruit with thick russet leathery
       rind and juicy yellow or reddish flesh [syn: mamey,
       mammee, mammee apple]