neutrino definition
Full Definition of NEUTRINO. : an uncharged elementary particle that is believed to have a very small mass, that has any of three forms, and that interacts only rarely with other particles.â neuÂ·triÂ·noÂ·less \-lÉs\ adjective.See neutrino defined for English-language learners. an uncharged elementary particle that is believed to have a very small mass, that has any of three forms, and that interacts only rarely with other particles. â neuÂ·triÂ·noÂ·less \-lÉs\ adjective. See neutrino defined for English-language learners.