- adjective referring to something that does not allow light or other rays to pass through it
- A body, material, or medium which does not pass radiant energy, such as light, or sound.
- A body, material, or medium which does not pass one form of radiant energy, such as ultraviolet light, but passes others, such as visible light.
- A body, material, or medium which does not pass one type of particle, such as ions, but passes others, such as photons.
- noun a photographic pigment that can block out areas of a negative
- noun ink used to cover up parts of a film
- verb to remove spots, blemishes or other parts of a negative which are to be cut out from a plate, by painting over them with an opaque ink