Outer product
A matrix with every possible product of elements from two vectors,
\begin{equation*} \vec{u} \otimes \vec{v} = \vec{u} \, \vec{v}^\mathsf{T} = \begin{pmatrix} u_1 \\ \vdots \\ u_m \end{pmatrix} \begin{pmatrix} v_1 & \cdots & v_n \end{pmatrix} = \begin{pmatrix} u_1 v_1 & \cdots & u_1 v_n \\ \vdots & \ddots & \vdots \\ u_m v_1 & \cdots & u_m v_n \end{pmatrix}. \end{equation*}