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Fermat's principle

Fermat's principle proper noun: the principle, which links geometrical optics (or "ray optics") with wave optics, that the path traversed by a ray between two given points is: (in the original "strong" formulation) the one that takes the least time, or (in a weaker but more general formulation) one that takes a time that is "stationary" with respect to variations of the path (so that, loosely speaking, a small change in the ray path entails a very small change in the traversal time).

Proper noun

Fermat's principle

  1. The principle, which links geometrical optics (or "ray optics") with wave optics, that the path traversed by a ray between two given points is: (in the original "strong" formulation) the one that takes the least time, or (in a weaker but more general formulation) one that takes a time that is "stationary" with respect to variations of the path (so that, loosely speaking, a small change in the ray path entails a very small change in the traversal time).
    • But we now see that, if we use Fermat's principle, a fundamental result of any wave theory, and combine it with de Broglie's assumption about the relation between momentum and wavelength, we are led at once to the principle of least action.1960, John Clarke Slater, Quantum Theory of Atomic Structure, McGraw-Hill, page 39
    • […], Keller simply postulates these rays and finds their direction from Fermat's principle adapted to the hypothesis that these rays exist.1968, Petr Beckmann, The Depolarization of Electromagnetic Waves, Golem Press, page 108

Synonyms of Fermat's principle

Origin of Fermat's principle

First proposed by French mathematician Pierre de Fermat in 1662.

Questions about Fermat's principle

What does Fermat's principle mean?
Fermat's principle means the principle, which links geometrical optics (or "ray optics") with wave optics, that the path traversed by a ray between two given points is: (in the original "strong" formulation) the one that takes the least time, or (in a weaker but more general formulation) one that takes a time that is "stationary" with respect to variations of the path (so that, loosely speaking, a small change in the ray path entails a very small change in the traversal time).
What part of speech is Fermat's principle?
Fermat's principle is a proper noun.

Words near Fermat's principle in the dictionary

  1. Fermat primes
  2. Fermat pseudoprime
  3. Fermat pseudoprimes
  4. Fermat's Last Theorem
  5. Fermat's little theorem
  6. Fermat's principle
  7. Fermat's principle of least time
  8. Fermat-Apollonius circle
  9. Fermat-Apollonius circles
  10. Fermat-Torricelli point
  11. Fermat-Torricelli points

Source and license

Adapted from Wiktionary: Fermat's principle (page history and authors). Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws reformatted the entry and added links. Wiktionary data of 2026-09-02.

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