The story
For Willebrord van Roijen Snell, Dutch mathematician.
Etymology from Wiktionary, CC BY-SA 4.0.
Snell's law
Today it means: the law that, for a ray incident on the interface of two media, the sine of the angle of incidence times the index of the refraction of the first medium is equal to the sine of the angle of refraction times the index of refraction of the second medium Full definition →