vaccinium myrtillus

from The Collaborative International Dictionary of English v.0.48

Whortleberry \Whor"tle*ber`ry\, n. [AS. wyrtil a small shrub
   (dim. of wyrt wort) + E. berry. See {Wort}, and cf.
   {Huckleberry}, {Hurtleberry}.] (Bot.)
   (a) In England, the fruit of {Vaccinium Myrtillus}; also, the
       plant itself. See {Bilberry}, 1.
   (b) The fruit of several shrubby plants of the genus
       {Gaylussacia}; also, any one of these plants. See
       {Huckleberry}.
       [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Bilberry \Bil"ber*ry\, n.; pl. {Bilberries}. [Cf. Dan.
   b["o]lleb[ae]r bilberry, where b["o]lle is perh. akin to E.
   ball.]
   1. (Bot.) The European whortleberry ({Vaccinium myrtillus});
      also, its edible bluish black fruit.
      [1913 Webster]

            There pinch the maids as blue as bilberry. --Shak.
      [1913 Webster]

   2. (Bot.) Any similar plant or its fruit; esp., in America,
      the species {Vaccinium myrtilloides}, {Vaccinium
      c[ae]spitosum} and {Vaccinium uliginosum}.
      [1913 Webster]