adjective
1.
lacking in caution
made an incautious prediction
Synonyms: unalert, unguarded, unvigilant, unwary, unwatchful; compare careless 1
Related Word: imprudent, indiscreet, injudicious; bold, brash, impetuous, rash, reckless; neglectful, negligent, regardless, thoughtless, unmindful; hasty
Idioms: caught napping, off one's guard
Contrasted words: careful, circumspect, judicious, wary, watchful; discreet, judicious, prudent; sensible, thoughtful, wise
Antonyms: cautious
2.
Synonyms: rash 1, brash, hasty, hotheaded, ill-advised, inconsiderate, mad-brained, madcap, reckless, thoughtless
Antonyms: cautious
3.
Synonyms: irresponsible , carefree, careless, feckless, reckless, uncareful, wild