neutrino

n. uncharged particle with almost no mass (Physics)

Neutrinos are elementary particles that travel close to the speed of light, lack an electric charge, are able to pass through ordinary matter almost undisturbed, and are thus extremely difficult to detect. Neutrinos have a minuscule, but non-zero, mass too small to be measured as of 2007. They are usually denoted by the Greek letter ν (nu).
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Noun
1. an elementary particle with zero charge and zero mass
(hypernym) lepton

n. neutrino, uncharged particle with almost no mass (Physics)

n. neutrino, uncharged particle with almost no mass (Physics)