1. Hypernyms ("Cardioid" is a kind of): epicycloid (a line generated by a point on a circle rolling around another circle)

2. The Cardioid is a degenerate case of the limaçon.It is also a 1-cusped epicycloid (with ) and is the catacaustic formed by rays originating at a point on the circumference of a circle and reflected by the circle.