Entry 1 sense Webster, 1913 Limaçon /(lē̇`mȧ`sôN")/ · Li·ma·çon · IPA 01 n. A curve of the fourth degree, invented by Pascal. Its polar equation is r = a cos θ + b. 1. A curve of the fourth degree, invented by Pascal. Its polar equation is r = a cos θ + b.(Geom.)