The Collaborative International Dictionary of English v.0.48:

Orange \Or"ange\ ([o^]r"[e^]nj), n. [F.; cf. It. arancia,
   arancio, LL. arangia, Sp. naranjia, Pg. laranja; all fr. Ar.
   n[=a]ranj, Per. n[=a]ranj, n[=a]rang; cf. Skr. n[=a]ranga
   orange tree. The o- in F. orange is due to confusion with or
   gold, L. aurum, because the orange resembles gold in color.]
   [1913 Webster]
   1. The fruit of a tree of the genus Citrus (Citrus
      Aurantium). It is usually round, and consists of pulpy
      carpels, commonly ten in number, inclosed in a leathery
      rind, which is easily separable, and is reddish yellow
      when ripe.
      [1913 Webster]

   Note: There are numerous varieties of oranges; as, the
         bitter orange, which is supposed to be the original
         stock; the navel orange, which has the rudiment of a
         second orange imbedded in the top of the fruit; the
         blood orange, with a reddish juice; and the horned
         orange, in which the carpels are partly separated.
         [1913 Webster]

   2. (Bot.) The tree that bears oranges; the orange tree.
      [1913 Webster]

   3. The color of an orange; reddish yellow.
      [1913 Webster]

   Mandarin orange. See Mandarin.

   Mock orange (Bot.), any species of shrubs of the genus
      Philadelphus, which have whitish and often fragrant
      blossoms.

   Native orange, or Orange thorn (Bot.), an Australian
      shrub (Citriobatus parviflorus); also, its edible yellow
      berries.

   Orange bird (Zool.), a tanager of Jamaica (Tanagra zena);
      -- so called from its bright orange breast.

   Orange cowry (Zool.), a large, handsome cowry (Cypraea
      aurantia), highly valued by collectors of shells on
      account of its rarity.

   Orange grass (Bot.), an inconspicuous annual American plant
      (Hypericum Sarothra), having minute, deep yellow
      flowers.

   Orange oil (Chem.), an oily, terpenelike substance obtained
      from orange rind, and distinct from neroli oil, which is
      obtained from the flowers.

   Orange pekoe, a kind of black tea.

   Orange pippin, an orange-colored apple with acid flavor.

   Quito orange, the orangelike fruit of a shrubby species of
      nightshade (Solanum Quitoense), native in Quito.

   Orange scale (Zool.) any species of scale insects which
      infests orange trees; especially, the purple scale
      (Mytilaspis citricola), the long scale (Mytilaspis
      Gloveri), and the red scale (Aspidiotus Aurantii).
      [1913 Webster]

WordNet (r) 3.0 (2006):

orange pekoe
    n 1: a superior grade of black tea; grown in India and Sri Lanka
         and Java [syn: orange pekoe, pekoe]