densitometer

Etymology

density + -o- + -meter

densitometer means A device that measures the optical density of a material; especially to test film and print quality. Lexicurio rates it Rare gem — a strength score of 84 out of 100.

noun

A device that measures the optical density of a material; especially to test film and print quality.
A device that measures the specific gravity of a substance; a densimeter.