The term 'Property of a Subatomic Particle' can be summarized by the crossword solution SPIN, which stands for 'SPIN Angular Momentum'. SPIN Angular Momentum is a fundamental property of subatomic particles, such as electrons, protons, and neutrons. It is a measure of the intrinsic angular momentum of a particle, which is the rotational motion of the particle around its own axis. This property is important in quantum mechanics and is related to the magnetic moment of a particle.