sp3d hybridization refers to the combination of one s orbital, three p orbitals, and one d orbital to form five new equivalent orbitals in an atom.
Orbital: An area around the nucleus of an atom where electrons are most likely to be found.
The electrons in the outermost shell of an atom that participate in chemical bonding.
Hybrid Orbitals: Orbitals that result from the mixing of different kinds of atomic orbitals on the same atom.