Meanings
- engineeringThe 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).
1976, Donald E. Tilley, Walter Thumm, Physics for College Students, Cummings Publishing Company, page 558, […] students wishing to pursue this branch of physics further will find that refraction too can be explained in terms of Fermat's principle.
2 more examples
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 108Synonyms: Fermat's principle of least time, principle of least time
Synonyms & antonyms
proper nounThe 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).
Origin
First proposed by French mathematician Pierre de Fermat in 1662.
Full word history & related roots →Translations
Chinese Mandarin 費馬原理 /费马原理
- 費馬原理 /费马原理 (Fèimǎ yuánlǐ)principle in optics
French principe de Fermat
- principe de Fermatprinciple in optics
German Fermatsches Prinzip
- Fermatsches Prinzipprinciple in optics
Polish zasada Fermata
- zasada Fermataprinciple in optics
Cite this entry
Fermat's principle. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/Fermat's%20principle
“Fermat's principle.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Fermat's%20principle. Accessed November 4, 2026.
WatkinsX Dictionary, s.v. “Fermat's principle,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/Fermat's%20principle.
Source: Fermat's principle on Wiktionary, CC BY-SA 4.0.