A neutrino is a fermion that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small (-ino) that it was long thought to be zero. The rest mass of the neutrino is much smaller than that of the other known elementary particles. The weak force has a very short range, the gravitational interaction is extremely weak due to the very small mass of the neutrino, and neutrinos do not participate in the electromagnetic interaction or the strong interaction. Thus, neutrinos typically pass through normal matter unimpeded and undetected.

न्यूट्रिनो (Neutrino) यह एक नया कण (Particle) है जिसका सर्वप्रथम आविष्कार सन्‌ १९३० में पौली ने किया था। इस कण का प्रथम सैद्धांतिक आधार प्रसिद्ध भौतिकीविद फर्मी ने सन्‌ १९३४ में बतलाया।