cardioid

By surface analysis, cardi- +‎ -oid.

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cardioid (plural cardioids)

1. (geometry) An epicycloid with exactly one cusp; the plane curve with polar equation ${\displaystyle \rho =1+\cos \,\theta }$ - approximately heart-shaped

cardioid (comparative more cardioid, superlative most cardioid)

1. Having this characteristic shape
2. (of a microphone) sensitive in front, but not behind or at the sides

• caridoid, cidaroid