Definition of "neutrino" []

• Any of three electrically neutral subatomic particles in the lepton family. See Table at subatomic particle. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "This means e.g. that the electron and the neutrino belong to the same family of particles; the neutrino is the electron's little brother."
• "For example, a positively charged pion decaying to a positively charged muon and a muon neutrino is the mirror process of a negatively charged pion decaying to a negatively charged muon and a muon antineutrino."
• "The neutrino is an elementary particle, which was postulated in 1930 by Wolfgang"