c. 1300, formal term of address to a lady (a woman of rank or authority, or the mistress of a household), from Old French ma dame, literally "my lady," from Latin mea domina (see Donna, and compare madonna). It became a conventional term of address to women of any degree (but chiefly to the married and matronly); also "a woman of fashion or pretension" (often with a suggestion of disparagement) by 1590s. From 1719 as "a courtesan, a prostitute;" the meaning "female owner or manager of a brothel" is attested by 1871.

The title of Madam is sometimes given here, and generally in Charleston (S. Carolina), and in the South, to a mother whose son has married, and the daughter-in-law is then called Mrs. By this means they avoid the inelegant phraseology of old Mrs. A., or the Scotch, Mrs. A senior. [Sir Charles Lyell, "A Second Visit to the United States of North America," 1849]

Proto-Indo-European root meaning "house, household." It represents the usual Indo-European word for "house" (Italian, Spanish casa are from Latin casa "cottage, hut;" Germanic *hus is of obscure origin).

It forms all or part of: Anno Domini; belladonna; condominium; dame; damsel; dan "title of address to members of religious orders;" danger; dangerous; demesne; despot; Dom Perignon; domain; dome; domestic; domesticate; domicile; dominate; domination; dominion; domino; don (n.) "Spanish, Italian, and Portuguese title of respect;" Donna; dungeon; ma'am; madam; madame; mademoiselle; madonna; major-domo; predominant; predominate; timber; toft.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit damah "house;" Avestan demana- "house;" Greek domos "house," despotēs "master, lord;" Latin domus "house," dominus "master of a household;" Armenian tanu-ter "house-lord;" Old Church Slavonic domu, Russian dom "house;" Lithuanian dimstis "enclosed court, property;" Old Norse topt "homestead."

In colonial India and south Asia, "a European lady," by 1857, a hybrid from the local pronunciation of English ma'am + Hindi and Urdu sahib "master" (see sahib).

also school-marm, "female school teacher," 1834, American English colloquial, in the popular countrified humor writing of "Major Jack Downing" of Maine (Seba Smith); a variant of school-ma'am (1828), from school (n.1) + ma'am. See R. Used figuratively from 1887 in reference to patronizing and priggish instruction.

School-mistress "woman who teaches in a school" is attested from c. 1500 (mid-14c. as a surname, scole-maistres). School-dame (1650s) was generally "an old woman who keeps a school for small children."