Madcap
WordNet
adjective
(1) Characterized by undue haste and lack of thought or deliberation
"A hotheaded decision"
"Liable to such impulsive acts as hugging strangers"
"An impetuous display of spending and gambling"
"Madcap escapades"; (`brainish' is archaic)
noun
(2) A reckless impetuous irresponsible person
WiktionaryText
Adjective
- impulsive, hasty or reckless; capricious.
- The film featured a madcap car chase that went right through a crowded café.