madame

a title or form of address for a woman, formerly for a married woman and now commonly for any adult woman regardless of marital status, used both in direct and third-person address; madam, Mrs. or Ms.; a title used with a woman's full name or surname, or (in childish language) her first name; lady, woman; the female employer of a domestic servant

“Bonjour, madame, comment puis-je vous aider ?” — Hello, ma'am, how can I help you?

From Old French ma dame (“my lady”), equivalent to ma + dame.