TOPICS
Symmetric
A mathematical object is symmetric if it is invariant ("looks the same") under a symmetry transformation.
A function, matrix, etc., is symmetric if it remains unchanged in sign when indices are reversed. For example, 
is symmetric since 
.
See also
Antisymmetric, Symmetric Function, SymmetryExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Symmetric." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Symmetric.html