n 1  :  a quantum characteristic of an elementary particle that is visualized as the rotation of the particle on its axis and that is responsible for measurable angular momentum and magnetic moment  2  :  the angular momentum which is associated with spin, whose magnitude is quantized, and which may assume either of two possible directions : also  :  the angular momentum of a system of elementary particles derived from their spins and orbital motions - see SPIN ECHO SPIN LABEL  .
 
 
 
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