Madam, Madame, ma'am, or Mme is a title for a woman. It is derived from the French madame (see different meanings of madame here), the equivalent of Mrs. or Ms., and literally signifying "my lady." The plural of madam in this sense is mesdames. The French madame is in turn derived from the Latin mea domina meaning 'my mistress' of the home (domus). "Madam" may also refer to a woman who runs a brothel.

Use as a form of address

Madam is used in direct address, without the woman's name, for example when addressed by a stranger: May I help you, madam? In the United States and in Canada, "Ma'am" is usually used. The male equivalent is sir. Spelling of the word is often quarreled; some argue it is spelled "M'am" while it is widely accepted the correct form is "Ma'am". When addressing a letter to the holder of a particular position (for example, the editor of the Letters to the Editor column in a newspaper) withour knowing the name of the adressee and if it is a man or a woman, it is common to address the letter with "Dear Sir or Madam".

Formal address and protocol

In English-speaking countries, the wife of a foreign dignitary is called Madame (note final 'e') in direct address and formal correspondence, rather than the equivalent word in the person's native language (Señora, Frau etc.).

After addressing her as "Your Majesty," it is proper to address The Queen of the United Kingdom as "Ma'am" for the remainder of the conversation, with the pronunciation as in "ham" and not as in "farm".

Usage of "Ma'am" is common in the Southern United States and in Western Canada.

In composed titles

Madam is also used as the equivalent of Mister (Mr) in composed titles, such as Madam Justice, Madam Speaker, Madam President. Most of these titles are usually used only in direct address, without the woman's last name: one would say President Smith, not Madam President Smith, even if one would address her to her face as Madam President.

However, the title Madam Justice is used in third-person reference: Madam Justice Louise Arbour, Madam Justice Arbour.

In the United States Supreme Court, in the Canada Supreme Court, and the superior courts of Australia, rather than adopting the title Madam Justice for female justices, the title Mr Justice was replaced simply by Justice. Likewise, female presidents of the Republic of Ireland have preferred to be addressed simply as President in direct address, rather than Madam President. Female judges of the High Court of Justice of England and Wales are titled Mrs Justice rather than Madam Justice, regardless of marital status. However, District Judges are referred to as either Madam or Ma'am.