Source : Webster's Revised Unabridged Dictionary (1913)

Easel \Ea"sel\, n. [D. ezel ass, donkey, hence, easel, or G.
   esel; akin to E. ass. See {Ass}.]
   A frame (commonly) of wood serving to hold a canvas upright,
   or nearly upright, for the painter's convenience or for
   exhibition.

   {Easel picture}, {Easel piece}, a painting of moderate size
      such as is made while resting on an easel, as
      distinguished from a painting on a wall or ceiling.

Source : WordNet®

easel
     n : an upright tripod for displaying something (usually an
         artist's canvas)