A curve such that the polar of each point with respect to a given conic is tangential to another curve; (also) a polygon such that the polar of each point is a side of another given polygon.
Origin
Mid 19th century.
Definition of polar reciprocal in US English:
polar reciprocal
noun
A curve such that the polar of each point with respect to a given conic is tangential to another curve; (also) a polygon such that the polar of each point is a side of another given polygon.