The Collaborative International Dictionary of English v.0.48:

Blueberry \Blue"berry\, n. [Cf. Blaeberry.] (Bot.)
   The berry of several species of Vaccinium, an ericaceous
   genus, differing from the American huckleberries in
   containing numerous minute seeds instead of ten nutlets. The
   commonest species are Vaccinium Pennsylvanicum and
   Vaccinium vacillans. Vaccinium corymbosum is the tall
   blueberry.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Vaccinium corymbosum
    n 1: high-growing deciduous shrub of eastern North America
         bearing edible blueish to blackish berries with a distinct
         bloom; source of most cultivated blueberries [syn: high-
         bush blueberry, tall bilberry, swamp blueberry,
         Vaccinium corymbosum]