Any of the baryons that are not nucleons, have a mass greater than that of the neutron, and are not stable.
(particle physics) An unstable baryon that is more massive than a neutron.
Any of various baryons, other than the proton and neutron, that are unstable. The lambda particle is such an example. Hyperons are heavier than protons and neutrons, and they have nonzero strangeness .