Source : Webster's Revised Unabridged Dictionary (1913)

   {Lily of the valley} (Bot.), a low perennial herb
      ({Convallaria majalis}), having a raceme of nodding,
      fragrant, white flowers.

Source : WordNet®

lily of the valley
     n : low-growing perennial plant having usually two large oblong
         lanceolate leaves and a raceme of small fragrant nodding
         bell-shaped flowers followed by scarlet berries [syn: {lilies
         of the valley}, {May lily}, {Convallaria majalis}]