from
The Collaborative International Dictionary of English v.0.48
Madam \Mad"am\, n.; pl. {Madams}, or {Mesdames}. [See {Madame}.]
1. A gentlewoman; -- an appellation or courteous form of
address given to a lady, especially an elderly or a
married lady; -- much used in the address, at the
beginning of a letter, to a woman. The corresponding word
in addressing a man is {Sir}; often abbreviated ma'am when
used as a term of address.
[1913 Webster]
2. The woman who is in charge of a household.
[PJC]
3. The woman who is in charge of a brothel.
[PJC]