The Collaborative International Dictionary of English v.0.48:

Barberry \Bar"ber*ry\, n. [OE. barbarin, barbere, OF. berbere.]
   (Bot.)
   A shrub of the genus Berberis, common along roadsides and
   in neglected fields. Berberis vulgaris is the species best
   known; its oblong red berries are made into a preserve or
   sauce, and have been deemed efficacious in fluxes and fevers.
   The bark dyes a fine yellow, esp. the bark of the root. [Also
   spelt berberry.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

barberry
    n 1: any of numerous plants of the genus Berberis having prickly
         stems and yellow flowers followed by small red berries