The Collaborative International Dictionary of English v.0.48:

Camaieu \Ca*ma"ieu\, n. [F.; of unknown origin. Cf. Cameo.]
   1. A cameo. [Obs.] --Crabb.
      [1913 Webster]

   2. (Fine Arts) Painting in shades of one color; monochrome.
      --Mollett.
      [1913 Webster]