The Collaborative International Dictionary of English v.0.48:
Breadth \Breadth\ (br[e^]dth), n. [OE. brede, breede, whence
later bredette, AS. br[=ae]du, fr. br[=a]d broad. See
1. Distance from side to side of any surface or thing;
measure across, or at right angles to the length; width.
2. (Fine Arts) The quality of having the colors and shadows
broad and massive, and the arrangement of objects such as
to avoid to great multiplicity of details, producing an
impression of largeness and simple grandeur; -- called
also breadth of effect.
Breadth of coloring is a prominent character in the
painting of all great masters. --Weale.