A fermion that is its own antiparticle (as opposed to a Dirac fermion, where this is not the case). The idea of a Majorana fermion was proposed by Ettore Majorana (1906–?) in 1937, shortly before his mysterious disappearance. It is not known whether neutrinos are Majorana or Dirac fermions. It is natural for many of the fermions in supersymmetry to be Majorana fermions. Majorana fermions can occur as quasiparticles in the theory of condensed-matter physics.