A respectful term for the wife of a master or proprietor, often used in traditional or merchant family contexts. Somewhat dated; in modern settings 奥様 or 女将 may be more common.
The mistress of that traditional restaurant is a very friendly person.
The madam was sitting at the cashier's desk keeping the books.
Standard kanji spelling.
Mixed kana-kanji spelling, also used.
The term is composed of 御 (honorific prefix) + 寮人 (originally a court official or steward), but the exact historical derivation of the meaning 'mistress of a house' is uncertain.