Of a matrix, satisfying A^\textsf{T}=-A, i.e. having entries on one side of the diagonal that are the inverses of their correspondents on the other side of the diagonal and having only zeroes on the diagonal.
\left(\begin{array}{ccc}0 & 2 & 3\\ -2 & 0 & -4\\ -3 & 4 & 0\end{array}\right)