In the theory of supersymmetry, every Standard Model particle has a corresponding "sparticle" partner with a spin that differs by 1/2. Superpartner is the general term for these partner particles. The superpartner of a boson is always a fermion, and the superpartner of a fermion is always a boson. The superpartners have the same mass, charge, and other internal properties as their Standard Model counterparts. See: supersymmetry.