any particle that obeys Bose-Einstein statistics but not the Pauli exclusion principle; all nuclei with an even mass number are bosons
A particle with totally symmetric composite quantum states, which exempts them from the Pauli exclusion principle, and that hence obeys Bose-Einstein statistics. They have integer spin. Among them are many elementary particles, and some (gauge bosons) are known to carry the fundamental forces. Compare fermion.
A boatswain.