Orbital hybridization

A change of atomic-orbital basis used to construct directed local bonding orbitals. $sp$, $s{p}^2$ and $s{p}^3$ describe idealized combinations; they are model descriptions rather than unique experimental labels for every bonded atom.

A linear combination of atomic orbitals used in a localized description of directional bonding or lone pairs. Hybrid labels are models rather than directly observable fixed atomic states.