The set closure 
of a star 
at a vertex 
of a simplicial complex 
.
Closed Star
See also
Simplicial Complex Link, StarExplore with Wolfram|Alpha
References
Munkres, J. R. Elements of Algebraic Topology. New York: Perseus Books Pub., 1993.Referenced on Wolfram|Alpha
Closed StarCite this as:
Weisstein, Eric W. "Closed Star." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ClosedStar.html