心形曲线; 心脏线; 心状的
Cardioid \Car"di*oid\, n. [Gr. kardio-eidh`s heart-shaped; kardi`a heart + e'i^dos shape.] (Math.) An algebraic curve, so called from its resemblance to a heart.
cardioid n : an epicycloid in which the rolling circle equals the fixed circle