Definitions for: Folium

[n] a thin layer or stratum of (especially metamorphic) rock

Webster (1913) Definition: 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 x^3 + y^3 = axy.

See Also: formation, geological formation, geology