The Collaborative International Dictionary of English v.0.48:

baryon \baryon\ n.
   1. any of the elementary particles having a mass equal to or
      greater than that of a proton and that participate in
      strong interactions; a hadron with a baryon number of +1.

   Syn: heavy particle.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

baryon
    n 1: any of the elementary particles having a mass equal to or
         greater than that of a proton and that participate in
         strong interactions; a hadron with a baryon number of +1
         [syn: baryon, heavy particle]