Folium

Fo"li*um (?), n.; pl. E. Foliums (#), L. Folia (#). [L., a leaf.] 1. A leaf, esp. a thin leaf or plate.

2. (Geom.) A curve of the third order, consisting of two infinite branches, which have a common asymptote. The curve has a double point, and a leaf-shaped loop; whence the name. Its equation is x³ + y³ = axy.