noun
- Plural of fermi; a unit of length equal to one quadrillionth of a meter, used in nuclear and particle physics.
Usage: physics; technical
Examples
- The nucleus of an atom has a radius measured in fermis.
- Physicists use fermis to describe distances at the subatomic scale.
- The fermi unit is named after physicist Enrico Fermi.
- Particle interactions occur at distances of a few fermis.