"blemish, spot," late 15c., from Latin macula "a spot, stain" (see macula), perhaps via French macule. Compare macle.

late 13c., "disordered in intellect, demented, crazy, insane," from Old English gemædde "out of one's mind" (usually implying also violent excitement), also "foolish, extremely stupid," earlier gemæded "rendered insane," past participle of a lost verb *gemædan "to make insane or foolish," from Proto-Germanic *gamaidjan, demonstrative form of *gamaidaz "changed (for the worse), abnormal" (source also of Old Saxon gimed "foolish," Old High German gimeit "foolish, vain, boastful," Gothic gamaiþs "crippled, wounded," Old Norse meiða "to hurt, maim").

This apparently is from the Germanic intensive prefix *ga- + PIE *moito-, past participle of root *mei- (1) "to change, go, move" (source also of Latin mutare "to change," migrare "to change one's place of residence"). In Middle English usurped the place of the more usual Old English word, wod (see wood (adj.)).

The meanings "beside oneself with excitement or enthusiasm, under the influence of uncontrollable emotion" and "enraged, furious, beside oneself with anger" are attested from early 14c., but the latter was deplored by Rev. John Witherspoon (1781) as an Americanism. It now competes in American English with angry for this sense. Of animals, "affected with rabies, furious from disease" from late 13c.

To do something like mad "recklessly, as if mad or crazy" is by 1650s. Phrase mad as a March hare is attested from 1520s, via notion of breeding season; mad as a hatter is from 1829 as "demented," 1837 as "enraged," according to a modern theory supposedly from erratic behavior caused by prolonged exposure to poison mercuric nitrate, used in making felt hats. For mad as a wet hen see hen.

Mad money, which a young woman carries for use in getting home when she and her date have a falling out, is attested by 1922; mad scientist, one so eccentric as to be dangerous or evil, is by 1891. Mad Libs, the word game (based on the idea in consequences, etc.), was first published in 1958

"strangely, madly," late 14c., from mad (adj.).

"make furious, enrage," also "be out of one's mind," late 14c., from Old English gemædan "make insane" (see mad (adj.)).

large island lying to the east of and near Africa, from Mogadishu, the name of the city in Somalia, due to an error by Marco Polo in reading Arabic, whereby he thought the name was that of the island. There is no indigenous name for the whole island. Related: Madagascan; Madagascarian; Madagascarene.

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]

formal term of address to a lady, 1590s, see madam, which is an earlier borrowing of the same French phrase. Originally a title of respect for a woman of rank, now given to any married woman. It is more formal or affected than madam. OED recommends madam as an English title, madame in reference to foreign women.

1580s, noun ("person who acts madly or wildly") and adjective ("wild, harum-scarum), from mad (adj.) + cap, used here figuratively for "head." Related: Madcappery. Compare mad-brain "rash or hot-headed person" (1560s).

"to drive to distraction, make crazy" (transitive), 1822; earlier in intransitive sense "to be or become mad" (1735), from mad (adj.) + -en (1). Related: Maddened; maddening. The earlier verb was simply mad (14c.), from the adjective.