madcap

UK: /ˈmædkæp/ US: /ˈmædˌkæp/ ,(mad′kap′)

WordReference Random House Learner's Dictionary of American English © 2026

mad•cap /ˈmædˌkæp/   adj. [before a noun]

1. recklessly foolish;
   impulsive;
   rash:
   madcap schemes.

n. [countable]

2. a madcap person.

WordReference Random House Unabridged Dictionary of American English © 2026

mad•cap  (mad′kap′), adj. 

1. wildly or heedlessly impulsive;
   reckless;
   rash:
   a madcap scheme.

n. 

2. a madcap person.

• mad + cap¹ 1580–90

Collins Concise English Dictionary © HarperCollins Publishers::

madcap / ˈmædˌkæp/ adjective

1. impulsive, reckless, or lively

noun

1. an impulsive, reckless, or lively person

Etymology: 16th Century: from mad + cap (in the figurative sense: head)