neutrino

noun1

1. •
   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.

   • But researchers at the CERN lab near Geneva claim they have recorded neutrinos, a type of tiny particle, travelling faster than the barrier of 186,282 miles (299,792 kilometres) per second. — 2011