The Collaborative International Dictionary of English v.0.48:

Vaccinium \Vac*cin"i*um\, n. [L., the blueberry, or
   whortleberry.] (Bot.)
   A genus of ericaceous shrubs including the various kinds of
   blueberries and the true cranberries.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Vaccinium
    n 1: evergreen or deciduous berry-bearing shrubs of northern
         hemisphere: cranberries; blueberries [syn: Vaccinium,
         genus Vaccinium]