irresponsible
ir-re-spon-si-ble
adjective
Not showing a proper sense of duty or concern for the consequences of one's actions.
"His irresponsible behaviour caused many issues."
Thesaurus
Synonyms: idle, harum-scarum, feckless, trigger-happy, slaphappy, happy-go-lucky, carefree, freewheeling, loose, unreliable, do-nothing, devil-may-care
Antonyms: responsible