Learn how to say Orthochromatic correctly in English with this tutorial pronunciation video.
Oxford dictionary definition of the word orthochromatic:
(of black-and-white photographic film) sensitive to all visible light except red. Orthochromatic film can therefore be handled in red light in the darkroom but does not produce black-and-white tones that correspond very closely to the colours seen by the eye. Often contrasted with panchromatic.