WordReference Random House Unabridged Dictionary of American English © 2026
re•frac•tom•e•ter
(rē′frak tom′i tər),USA pronunciation n. [Optics.]
re•frac•to•met•ric
(ri frak′tə me′trik),USA pronunciation adj.
re′frac•tom′e•try, n.
- Opticsan instrument for determining the refractive index of a substance.
- 1875–80; refract + -o- + -meter