Source : Webster's Revised Unabridged Dictionary (1913)

   {Lily pad}, the large floating leaf of the water lily. [U.
      S.] --Lowell.

   {Tiger lily} (Bot.), {Lilium tigrinum}, the sepals of which
      are blotched with black.

   {Turk's-cap lily} (Bot.), {Lilium Martagon}, a red lily with
      recurved sepals; also, the similar American lily, {L.
      superbum}.

   {Water lily} (Bot.), the {Nymph[ae]a}, a plant with floating
      roundish leaves, and large flowers having many petals,
      usually white, but sometimes pink, red, blue, or yellow.
      [See Illust. of {Nymph[ae]a}.]

Source : WordNet®

lily pad
     n : floating leaves of a water lily