Word Study
billon
CIDE DICTIONARY
billon, n. [F. Cf. Billet a stick.].
An alloy of gold and silver with a large proportion of copper or other base metal, used in coinage. [1913 Webster]
OXFORD DICTIONARY
billon, n. an alloy of gold or silver with a predominating admixture of a base metal.
Etymology
F f. bille BILLET(2)
For further exploring for "billon" in Webster Dictionary Online