from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Behaving or acting impulsively or rashly; wild.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. impulsive, hasty or reckless; capricious.
  • n. An impulsive, hasty, capricious person.
  • n. An insane person, a lunatic.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Inclined to wild sports; delighting in rash, absurd, or dangerous amusements.
  • adj. Wild; reckless.
  • n. A person of wild behavior; an excitable, rash, violent person.

from The Century Dictionary and Cyclopedia

  • n. A person who acts madly or wildly; a flighty or harebrained person; one who indulges in frolics.
  • Pertaining to or resembling a madcap; wild; harum-scarum.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • adj. characterized by undue haste and lack of thought or deliberation
  • n. a reckless impetuous irresponsible person


mad + cap1, head.
(American Heritage® Dictionary of the English Language, Fourth Edition)
1580s, mad +‎ cap (“head”), literally “crazy head”. Original literal sense “lunatic, crazy person”, now used figuratively. (Wiktionary)



Log in or sign up to get involved in the conversation. It's quick and easy.