From Longman Dictionary of Contemporary Englishmadammad‧am /ˈmædəm/ ●○○ noun 1 TALK TO somebodyWOMAN formal used to address a woman in a polite way, especially a customer in a shop SYN ma'am American English Are you being served, Madam?2 → Dear Madam3 → Madam President/Ambassador etc4 [countable]SY a woman who is in charge of a brothel5 → a (proper) little madam
Examples from the Corpus
madam• How do you do, Madam?• But, anyway, I said yes, because I thought I could escape from him easier than from madam.• She wanted to be that kind of madam.• Or do you prefer whisky-and-soda, madam?• As the madam, Daly received the £10 door money.• She was madam, all right, a proper little madam.From Longman Business DictionaryMadamMad‧am /ˈmædəm/ noun1a polite way of addressing a woman, such as a customer in a shopCan I help you Madam?2Dear Madam used at the beginning of a business letter to a woman whose name you do not know3Madam chairman/ambassador/president etc the title used when addressing a woman who has an important positionOrigin madam (1200-1300) Old French ma dame “my lady” 