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: Webster's Revised Unabridged Dictionary (1913)