a. A form of respectful or polite address (substituted for the name) originally used by servants in speaking to their mistress, and by people generally in speaking to a woman of high rank; subsequently used with progressively extended application, and now, though no longer as frequently as in previous centuries, employed in addressing a woman of whatever rank or position; the female counterpart of sir n. 1.The early occurrence of dame n. in the sense of mother suggests that in Old French and early Middle English ma dame was very commonly used by children to their mother; but in the extant examples the mother so addressed is a queen or a lady of very high rank. In Chaucer's time ( Prol. Canterbury Tales 376) to be addressed as madame was one of the advantages which a citizen's wife gained by her husband's being made alderman; this probably indicates the lowest social grade in which at that time the title could be claimed as a matter of customary right. In poetry of the 14th–15th cent. the lover often addresses his mistress as madame. Nuns (originally only the elder ones: see quot. a1450) were called madame down to the Reformation.While in French the title has (with certain customary exceptions) been confined to married women, in English this rule has not been generally adopted, though there are traces of a tendency in the 16–17th cent. to address married women as ‘madam’ and unmarried women as ‘mistress’.From the 17th to the early 20th cent. madam was the title normally used in addressing a letter to a woman of any rank, except where the use of the name (as in ‘Dear Mrs A.’, etc.) was considered acceptable (‘my lady’, etc., not being admitted in this context). Oral use of the title has declined gradually since the 18th cent. when it was often replaced by the contracted form ma'am n.¹, which is itself now much less frequently used; however, madam is still the word generally used by persons in positions of service to the public, spec. by sales assistants to female customers, and also as a polite or formal form of address to a woman, esp. one whose name is not known to the speaker.

b. In substitution for the name of a woman usually addressed as ‘madam’.

c. colloquial. Used in contempt or anger. Cf. senses 4, 5.

a. Prefixed to a first or sole name. Now archaic.

†b. madam regent n. = queen regent (in quot. c1475, the title of a dance tune). Also figurative. Obsolete.

c. Prefixed to a designation of rank or office. Cf. madame regent (sense 2b) and madame n. 3.

†d. In playful or derisive uses preceding any noun personified as a woman. Cf. sir n. 3a, 3b. Obsolete.

e. Prefixed to a surname: (a) the style of a married woman of some rank or position in the community (now rare in British usage); †(b) U.S. the style of a deceased woman of position (obsolete); (c) U.S. and perhaps formerly British: the style of a woman who has a married son (whose wife has the style of ‘Mrs’) (now rare); (d) Irish English and Scottish: the style of the wife of an Irish chieftain; subsequently also used by the wife of a Scottish chief, chieftain, or laird.

†a. A lady of rank or station. Also figurative and appositively. Obsolete.

b. The mistress of a house. Now U.S. regional and colloquial, Caribbean, and South African.

a. An affected fine lady.

†b. A kept mistress, a courtesan or prostitute. Obsolete.

c. colloquial. A conceited or precocious girl or young woman; a hussy, a minx; also applied to a female child, esp. in little madam.In quot. 1787, probably condescending rather than derisive or opprobrious.