Orthonormality Let “ ∣+⟩,∣−⟩\left\lvert + \right\rangle,\left\lvert - \right\rangle∣+⟩,∣−⟩ are orthonormal” mean both ∣+⟩,∣−⟩\left\lvert + \right\rangle,\left\lvert - \right\rangle∣+⟩,∣−⟩ are both orthogonal and Normal.