fermi
/ˈfɛrmi/
noun
- A unit of length used in nuclear physics, equal to one quadrillionth of a meter (10⁻¹⁵ meters). Also called a femtometer.
- Physicists measure distances inside the nucleus in fermis.
- The radius of a proton is about 0.84 fermi.
- One fermi is extremely small, much smaller than an atom.
Synonyms