FOLIUM
folium
(noun) a thin layer or stratum of (especially metamorphic) rock
Source: WordNet® 3.1
Etymology
Noun
folium (plural foliums or folia)
A leaf, especially a thin leaf or plate.
(geometry) A curve of the third order, consisting of two infinite branches having a common asymptote. The curve has a double point, and a leaf-shaped loop.
Source: Wiktionary
Fo"li*um, n.; pl. E. Foliums, L. Folia. Etym: [L., a leaf.]
1. A leaf, esp. a thin leaf or plate.
2. (Geom.)
Definition: 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.
Source: Webster’s Unabridged Dictionary 1913 Edition