Definition of antiparticle
: a subatomic particle identical to another subatomic particle in mass but opposite to it in electric and magnetic properties (such as sign of charge) that when brought together with its counterpart produces mutual annihilation; especially : a subatomic particle not found in ordinary matter
First Known Use of antiparticle
Learn More about antiparticle
Britannica.com: Encyclopedia article about antiparticle
Seen and Heard
What made you want to look up antiparticle? Please tell us where you read or heard it (including the quote, if possible).