A squark is a sfermion.
According to Wikipedia, in particle physics, a sfermion is the spin-0 superpartner particle (or sparticle) of its associated fermion. In supersymmetric extensions to the Standard Model (SM) each particle has a superpartner with spin that differs by 1⁄2. Fermions in the SM have spin-1⁄2 and therefore sfermions have spin 0. So a quark has a spin 1/2 and a squark has a spin 0.
In general the name sfermions is formed by prefixing an ‘s’ to the name of its superpartner, denoting that it is a scalar particle with spin 0. For instance, the electron’s superpartner is the selectron and the top quark’s superpartner is the stop squark.