Source : Webster's Revised Unabridged Dictionary (1913)

Greenweed \Green"weed`\, n. (Bot.)
   See {Greenbroom}.

Source : WordNet®

greenweed
     n : small Eurasian shrub having clusters of yellow flowers that
         yield a dye; common as weed in England and United States;
         sometimes grown as an ornamental [syn: {woodwaxen}, {dyer's
         greenweed}, {dyer's-broom}, {dyeweed}, {whin}, {woadwaxen},
          {Genista tinctoria}]