Photometry

noun

1. Measurement of the properties of light, especially luminous intensity.
2. The measurement of the relative amounts of light emitted by different sources.
3. Measurement of the amount of insufficiency of the external muscles of the eye; the scientific use of the phorometer.
4. In biology, the reactional movement, positive and negative, with an indifference point between, of organisms under changing intensity of illumination.
5. That branch of science which treats of the measurement of the intensity of light.