A particle, such as an electron, a proton, or a neutron, having half-integral spin and obeying statistical rules requiring that not more than one in a set of identical particles may occupy a particular quantum state.

• 费密子一种如电子、质子或中子等自旋为半整数的基本粒子，具有一种使得不可能有多于一个的粒子占有任何一个特殊的量子力学态的量子力学对称性