an elementary, electrically neutral particle with a very small mass
"Scientists detected the elusive neutrino passing through the Earth without interacting with any matter due to its tiny mass and lack of electrical charge."
An elementary particle that is classified as a lepton, and has an extremely small but nonzero mass and no electric charge. It interacts with the surroundings only via the weak force or gravitation, making it very difficult to detect.
"Scientists detected the elusive neutrino passing through tons of rock because it barely interacts with anything due to its lack of electric charge and tiny mass."