(geometry, inversive geometry) A circle or a line, the two being regarded as types of a single form.

Alternative form of generalized circle

plural of circle inversion

(geometry, inversive geometry, for a given circle with centre O and radius r) A transformation that maps any point P ≠ O to the point P’ on the ray from O through P for which OP × OP’ = r², and which maps O to the point at infinity.

plural of quality circle

plural of Apollonian circle

(archaeology) a prehistoric monument consisting of standing stones arranged in a circle.

plural of azimuth circle

plural of babysitting circle

plural of bolt circle