Today it means: 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. Full definition →
From Bose + -on. Named after Indian physicist Satyendra Nath Bose (1894–1974); coined by English physicist Paul Dirac in 1945 in a lecture titled Developments in Atomic Theory.
Clipping of boatswain.
Etymology from Wiktionary, CC BY-SA 4.0.