Does orthogonal beamforming mean $\mathbf f_a \cdot \mathbf f_b =0$? If i said that these two beamformings $\mathbf f_a $ and $ \mathbf  f_b $ are orthogonal to each other,does it mean $\mathbf  f_a \cdot \mathbf f_b \approx 0$ ?

Because i have see two paper about orthogonal beamforming,but they both doesn't mention this relation.i just want to make sure about that
Orthogonality might be considered in literature as background knowledge. The definition is somehow a converse version. If $\cdot $ denotes an inner product (or a dot or scalar product), and whenever 
 $\mathbf  f_a \cdot \mathbf f_b = 0$, then $f_a$ and  $f_b$ are said to be orthogonal.

Note that, if $\mathbf  f_a$ is zero, it is orthogonal to everything.