A convex set 
is centro-symmetric, sometimes also called centrally symmetric,
if it has a center 
that bisects every chord of 
through 
.
Centrosymmetric Set
Explore with Wolfram|Alpha
References
Croft, H. T.; Falconer, K. J.; and Guy, R. K. Unsolved Problems in Geometry. New York: Springer-Verlag, p. 7, 1991.Referenced on Wolfram|Alpha
Centrosymmetric SetCite this as:
Weisstein, Eric W. "Centrosymmetric Set." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/CentrosymmetricSet.html