Definitions for water lily
Random House Webster's College Dictionary
any of various aquatic plants of the genus Nymphaea, species of which have large, disklike, floating leaves and showy flowers, esp. N. odorata, of America, or N. alba, of Europe.
any related plant of the genus
Origin of water lily:
an aquatic plant of the family Nymphaeaceae
Any of various members of the Nymphaeaceae family that are tuberous plants, rooted in soil with leaves and flowers floating on the water surface.
a blossom or plant of any species of the genus Nymphaea, distinguished for its large floating leaves and beautiful flowers. See Nymphaea