Say you have a solution $\textbf{x}=(x_1,x_2,\ldots,x_n)$ to a system of equations. It turns out that $-\textbf{x}$ is also a solution. Is there accepted terminology for such a pair of solutions? (I don't think conjugate is it.) Is there terminology for the system that admits such solutions? (I don't think symmetric is general enough.)
Assume we're dealing with real numbers here.