interferometer

noun

Etymology: Etymology tree English interfer(e) Ancient Greek -ο- (-o-)der. Latin -o-bor. English -o- Proto-Indo-European *meh₁- Proto-Indo-European *-tḗr Proto-Indo-European *-trom Proto-Hellenic *-tron Ancient Greek -τρον (-tron) Ancient Greek μέτρον (métron)der. English -meter English interferometer From interfer(e) + -o- + -meter.

1. Any of several instruments that use the interference of waves to determine wavelengths and wave velocities, determine refractive indices, measure small distances, temperature changes, stresses, and many other useful measurements.