Main Entry: an·ti·par·ti·cle

Pronunciation: \ˈan-tē-ˌpär-ti-kəl, ˈan-ˌtī-\

Function: noun

Date: 1934

: a subatomic particle identical to another subatomic particle in mass but opposite to it in electric and magnetic properties (as sign of charge) that when brought together with its counterpart produces mutual annihilation; especially : a subatomic particle not found in ordinary matter