rash
Meaning: hasty, incautious
Usage: It’s best to think things over calmly and thoroughly, rather than make rash decisions.
impetuous
Meaning: rash; hastily done
Usage: Hilda’s impetuous decision to quit the club was made without thinking.
frenetic
Meaning: frenzied, hectic, frantic
Usage: In the hours between night and morning, the frenetic pace of city life slows to a lull.
wanton
Meaning: reckless, unrestrained, or deliberately harmful
Usage: The vandals showed wanton disregard for the garden by trampling the flowers.