a hypothetical type of neutrino that would obey a conservation law together with the tau lepton, with the total number of tau leptons and tau neutrinos minus the total number of their antiparticles remaining constant. Also called tau•on'ic neutri'no Pronunciation: (tô-on'ik, tou-). [key]Cf. lepton 2.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.