Meaning of developing-out paper

de•vel'op•ing-out' pa"per

Pronunciation: (di-vel'u-ping out', -vel"-), [key]
— Photog. Photog.
  1. a sensitized printing paper requiring development in order to bring out the image. Abbr.: D.O.P. Cf.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.