Definitions for "antineutron"
The antiparticle of a neutron. It has the same mass as a neutron, but a spin and magnetic moment opposite that of the neutron.
The antineutron is the antiparticle of the neutron. It was discovered by Bruce Cork in the year 1956, a year after the antiproton was discovered. An antineutron has the same mass as a neutron, and no net electric charge.