A unit of length equal to 10^-15 meters (one femtometer), used in nuclear and particle physics to measure subatomic distances.
Named after Enrico Fermi, the Italian-American physicist (1901-1954) who won the Nobel Prize for his work on nuclear reactions and made profound contributions to nuclear and particle physics.
A fermi is incomprehensibly small—the nucleus of an atom is about 100,000 fermi across, and subatomic particles like quarks operate at these scales, making this unit fundamental to understanding the quantum realm.
Complete word intelligence in one call. Free tier — 50 lookups/day.