hyperon

from WordNet (r) 3.0 (2006)

hyperon
    n 1: any baryon that is not a nucleon; unstable particle with
         mass greater than a neutron

from The Collaborative International Dictionary of English v.0.48

hyperon \hyperon\ n. (Physics)
   Any baryon that is not a nucleon; it is an unstable particle
   with a mass greater than that of a neutron.
   [WordNet 1.5]