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.
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            There pinch the maids as blue as bilberry. --Shak.
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   2. (Bot.) Any similar plant or its fruit; esp., in America,
      the species Vaccinium myrtilloides, Vaccinium
      c[ae]spitosum and Vaccinium uliginosum.
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