\begin{definition}[Definition:Orthogonal Basis of Vector Space]
Let $V$ be a vector space.
Let $\BB = \tuple {\mathbf e_1, \mathbf e_2, \ldots, \mathbf e_n}$ be a basis of $V$.
Then $\BB$ is an '''orthogonal basis''' {{iff}} $\mathbf e_1, \mathbf e_2, \ldots, \mathbf e_n$ are pairwise perpendicular.
\end{definition}