Madness is complete loss of reason, or wild foolishness. Sheer madness, drove him to madness, it would be madness.
As a description of mental illness it is old and now avoided in serious writing, though it survives in history and literature. In ordinary use it means an obviously bad idea — it would be madness to try. There is method in his madness is from Hamlet. Note mad, madly, madden.
1nounmadnessComplete loss of reason.
“In the play, the old king slowly falls into madness after losing his kingdom.”
2nounwildWild foolishness.
“It would be madness to drive home in this snowstorm.”
Too few real examples of this word to estimate which sense is commonest.
madness is a loss of reason.
Middle English madnes is mad plus -ness. Mad comes from Old English gemaed, meaning maimed or driven out of one's mind.
Middle English
madnes
English, today
madness
From Middle English madnes, madnesse; equivalent to mad + ness.
Etymology from Wiktionary, CC BY-SA