The state of being mad; insanity; mental disease. / The state of being angry. / rash folly

plural of madness

Insane; crazy, mentally deranged. / (chiefly US; informal in UK) Angry, annoyed. / (chiefly in the negative, informal) Used litotically to indicate satisfaction or approval.

(slang, New England, New York and UK, dialect) Intensifier; to a large degree; extremely; exceedingly; very; unbelievably.

(obsolete, intransitive) To be or become mad. / (now colloquial US, Jamaica) To madden, to anger, to frustrate.

Initialism of mutual assured destruction or mutually assured destruction. / Initialism of magnetic anomaly detector. / (genetics) Initialism of mothers against decapentaplegic.

(programming) Acronym of Michigan algorithm decoder, a programming language, a variant of ALGOL, developed in 1959 at the University of Michigan.

(archaic) Affected with madness; raging; furious.

present participle of mad

(UK, informal) Exceedingly eager, or having a keen desire or appetite for something. Particularly associated with and originally from the Madchester Era.