Definition of "louis"

(historical numismatics) Any gold or silver coin issued by the French kings from Louis XIII to Louis XVI and bearing their image on the obverse side, particularly the gold louis d'ors, originally a French form of the Spanish doubloon but varying in value between 10 and 24 livres.

(historical numismatics) The louis d'or constitutionnel, a 24-livre gold coin issued by the First French Republic.

(historical numismatics, informal) The franc germinal or napoleon, a similar gold coin issued by Napoleon and bearing his image on the obverse, worth 20 francs.