Source : Webster's Revised Unabridged Dictionary (1913)

Water nymph \Wa"ter nymph`\
   1. (Myth.) A goddess of any stream or other body of water,
      whether one of the Naiads, Nereids, or Oceanides.

   2. (Bot.) A water lily ({Nymph[ae]a}).

Source : WordNet®

water nymph
     n 1: submerged aquatic plant having narrow leaves and small
          flowers; of fresh or brackish water [syn: {naiad}]
     2: a water lily having large leaves and showy fragrant flowers
        that float on the water; of temperate and tropical regions
        [syn: {fragrant water lily}, {pond lily}, {Nymphaea
        odorata}]
     3: (Greek mythology) any nymph of the water
     4: a fairy that inhabits water [syn: {water sprite}]