madcap
1. [ adjective ] characterized by undue haste and lack of thought or deliberation
Synonyms: impetuous impulsive tearaway brainish hotheaded
Examples:

"a hotheaded decision" "liable to such impulsive acts as hugging strangers" "an impetuous display of spending and gambling" "madcap escapades" (`brainish' is archaic)

Related terms: archaism incautious
2. [ noun ] a reckless impetuous irresponsible person
Synonyms: swashbuckler hothead lunatic harum-scarum daredevil
Related terms: adventurer tearaway
Similar spelling:   matchup
  match-up