An Etymological Dictionary of Astronomy and Astrophysics

A closed curve with two loops resembling a figure 8. It is represented by the Cartesian equation (x² + y²)² = a²(x² - y²), where a is the greatest distance from the origin (pole) to the curve. Its polar equation is r² = a² cos 2θ.

See also: From L. Latin lemniscatus “adorned with ribbons,” from lemniscus “a pendent ribbon,” from Gk. lemniskos “ribbon;” First described by Jacques Bernoulli (1654-1705) in 1694.