Source : Webster's Revised Unabridged Dictionary (1913)

Leaflet \Leaf"let\, n.
   1. A little leaf; also, a little printed leaf or a tract.

   2. (Bot.) One of the divisions of a compound leaf; a foliole.

   3. (Zo["o]l.) A leaflike organ or part; as, a leaflet of the
      gills of fishes.

Source : WordNet®

leaflet
     n 1: a thin triangular flap of a heart valve [syn: {cusp}]
     2: part of a compound leaf
     3: a small book usually having a paper cover [syn: {booklet}, {brochure},
         {folder}, {pamphlet}]