concave polygon(n = noun.shape) - a polygon such that there is a straight line that cuts it in four or more points;
is a kind of polygon, polygonal shape
has particulars: reentering polygon, reentrant polygon
Antonym: convex polygon

concave, concave lens, concave polyhedron, concave shape, convex polygon, polygon, reentering polygon, reentrant polygon, regular polygon, spherical polygon