The Collaborative International Dictionary of English v.0.48:

macadamia nut \macadamia nut\ n.
   The hard-shelled nut of the Macadamia ternifolia, or the
   delicious edible nut without its shell; large quantities are
   produced in Hawaii and sold commercially.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

macadamia \macadamia\ n.
   1. any tree of the genus Macadamia, especially Macadamia
      ternifolia.

   Syn: macadamia tree.
        [WordNet 1.5]

   2. A macadamia nut.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Queensland nut \Queens"land nut`\ (Bot.)
   The nut of an Australian tree (Macadamia ternifolia). It is
   about an inch in diameter, and contains a single round edible
   seed, or sometimes two hemispherical seeds. So called from
   Queensland in Australia.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Macadamia ternifolia
    n 1: small Australian tree with racemes of pink flowers; widely
         cultivated (especially in Hawaii) for its sweet edible nuts
         [syn: macadamia nut, macadamia nut tree, Macadamia
         ternifolia]