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developing-out paper

American  
[dih-vel-uh-ping out, -vel-] / dɪˈvɛl ə pɪŋ ˈaʊt, -ˌvɛl- /

noun

Photography.
  1. a sensitized printing paper requiring development in order to bring out the image. D.O.P.


Etymology

Origin of developing-out paper

First recorded in 1915–20