noun Geometry. a plane curve such that if a straight
line is drawn from a certain fixed point, called the pole of the curve, to the curve, the part of the line intersected between the curve and its asymptote is always equal to a fixed distance. Equation:
r =
b ±
a sec(θ).
Origin: 1790–1800; <
Greek konchoeidḗs. See
conch,
-oid