refractometry

noun Optics.

1. an instrument for determining the refractive index of a substance.

noun

1. any instrument for determining the refractive index of a substance

n.

1. Measurement of the refractive index of a substance with a refractometer.
2. Use of a refractometer in determining the refractive error of the eye.

n.

1. Any of several instruments used to measure the refractive index of a substance.