plural of mad scientist

A lunatic; a highly eccentric person.

plural of mad hatter

(idiomatic) Extremely angry; furious to the point of outburst.

A stock character in popular fiction; a bumbling scientist working on unlikely ways to save the world, or a villainous one bent on destroying it.

(Britain, New Zealand, informal) Completely insane.

(uncountable, by ellipsis) Mad cow disease; bovine spongiform encephalopathy. / (countable) A cow afflicted with mad cow disease. / Used other than figuratively or idiomatically: see mad, cow.

(basketball, US) The NCAA Division I basketball championship tournaments.

Madness attributable to the heat of summer, or to the midsummer moon.

Alternative spelling of madman