Source : Webster's Revised Unabridged Dictionary (1913)

Ivorytype \I"vo*ry*type`\, n. (photog.)
   A picture produced by superposing a very light print,
   rendered translucent by varnish, and tinted upon the back,
   upon a stronger print, so as to give the effect of a
   photograph in natural colors; -- called also {hellenotype}.
   --Knight.