Source : Webster's Revised Unabridged Dictionary (1913)

Cranberry \Cran"ber*ry\ (kr[a^]n"b[e^]r*r[y^]), n.; pl.
   {Cranberries} (-r[i^]z). [So named from its fruit being ripe
   in the spring when the cranes return. --Dr. Prior.] (Bot.)
   A red, acid berry, much used for making sauce, etc.; also,
   the plant producing it (several species of {Vaccinum} or
   {Oxycoccus}.) The {high cranberry} or {cranberry tree} is a
   species of {Viburnum} ({V. Opulus}), and the other is
   sometimes called {low cranberry} or {marsh cranberry} to
   distinguish it.

Source : WordNet®

cranberry
     n 1: any of numerous shrubs of genus Vaccinium bearing
          cranberries
     2: very tart red berry used for sauce or juice