pentagram

noun1

1. •
   The shape of a five-pointed star constructed of five intersecting lines meeting at the vertices, such that a central pentagon and five surrounding isosceles triangles are formed; often with magical connotations; a 5/2 (or 5/3) star polygon.

   • Prove that the circles so belonging to the 6 pentagrams formed by 6 lines meet in a point, and so on; the series of theorems being interminable. — 1871