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fo·li·um

(fōle-əm)

n.pl. fo·li·a(-le-ə)

1. Geology A thin, leaflike layer or stratum occurring especially in metamorphic rock.

2. Mathematics A plane cubic curve having a single loop, a node, and two ends asymptotic to the same line.

[Latin, leaf; see bhel-³ in the Appendix of Indo-European roots.]

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folium

The equation of the folium of Descartes is x3 + y3 = 3axy.

Indo-European & Semitic Roots Appendices

Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

Indo-European Roots

Semitic Roots

The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.

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