費密子一種如電子、質子或中子等自旋為半整數的基本粒子，具有一種使得不可能有多於一個的粒子占有任何一個特殊的量子力學態的量子力學對稱性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.