bipack

[bahy-pak]
noun Photography.
  1. two separate films, each having an emulsion layer sensitive to a different color, held together with their emulsion layers facing for simultaneous exposure through the back of one.

Origin of bipack

First recorded in 1920–25; bi-1 + pack1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018