limacon

/ˈlɪməˌsɑn/
noun
  1. A heart-shaped curve traced by a point on a circle as it rolls around another circle of equal size; used in mathematics and geometry.
    • The limacon curve looks like a distorted circle with a dimple on one side.
    • In math class, we learned how to graph a limacon using polar coordinates.
    • The architect used a limacon shape for the design of the amphitheater's seating area.