Definition of "madcap"

madcap

/ˈmædkæp/

adjective
comparative more madcap, superlative most madcap
1. Hasty, impulsive, or reckless; capricious.
  Quotations
  The young Oxonian, on the contrary, had led out one of his maiden aunts, on whom the rogue played a thousand little knaveries with impunity; he was full of practical jokes, and his delight was to tease his aunts and cousins; yet, like all mad-cap youngsters, he was a universal favourite among the women.
  1820 January 1, Geoffrey Crayon [pseudonym; Washington Irving], “Christmas Eve”, in The Sketch Book of Geoffrey Crayon, Gent., number V, New York, N.Y.: […] C. S. Van Winkle, […], page 389
  My madcap plan was to catch that 0456, then hang about – probably for the 0624.
  2020 March 25, Steve Roberts, “Parly-vous?”, in Rail, page 68
noun
plural madcaps
1. An impulsive, hasty, capricious person.
2. (obsolete) An insane person, a lunatic.
  Quotations
  Why, what a madcap hath heaven lent us here!
  c. 1596 (date written), William Shakespeare, “The Life and Death of King Iohn”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act I, scene i]