Source : Webster's Revised Unabridged Dictionary (1913)

Madame \Ma`dame"\, n.; pl. {Mesdames}. [F., fr. ma my (L. mea) +
   dame dame. See {Dame}, and cf. {Madonna}.]
   My lady; -- a French title formerly given to ladies of
   quality; now, in France, given to all married women.
   --Chaucer.

Source : WordNet®

madame
     n : title used for a married Frenchwoman
     [also: {mesdames} (pl)]