An Etymological Dictionary of Astronomy and Astrophysics

An integer or half-integer on which the magnitude of a particle’s → spin angular momentum depends. It is expressed in units of → Planck’s constant divided by 2π. Called also spin, denoted s. The spin of a particle can only have a value that is zero or a multiple of 1/2. Particles with half-integer spins, 1/2, 3/2, 5/2, …, are → fermions. Particles with integer spin (0, 1, 2, …) are called → bosons.

See also: → spin; → quantum; → number.