adjective
lacking in responsibility
irresponsible behavior
Synonyms: carefree, careless, feckless, incautious, reckless, uncareful, wild
Related Word: undependable, unreliable, untrustworthy; unaccountable, unanswerable
Contrasted words: careful, cautious, discreet, heedful; dependable, reliable, trustworthy
Antonyms: responsible