Adolf Eugen Fick (3 September 1829 – 21 August 1901) was a German-born physician and physiologist.
Fick began his work in the formal study of mathematics and physics before realising an aptitude for medicine. He then earned his doctorate in medicine from the University of Marburg in 1851. As a fresh medical graduate, he began his work as a prosector.
In 1855, he introduced Fick's law of diffusion, which governs the diffusion of a gas across a fluid membrane. In 1870, he was the first to measure cardiac output, using what is now called the Fick principle.
Fick managed to double-publish his law of diffusion, as it applied equally to physiology and physics. His work led to the development of the direct Fick method for measuring cardiac output.
Fick's nephew, Adolf Gaston Eugen Fick, invented the contact lens.
In german, "fick" means "fuck".