not intentional

accidental

not producing the effect(s) desired

useless

(of) an animal without a backbone or spinal column, e.g. insects, worms

weak, useless

(especially) (doing things, done) without a proper sense of responsibility

careless, reckless

not thinking or caring about the effects, consequences

irresponsible in thought, deed

not working; not valuable

not working; not valuable

not anxious (about); not (emotionally) concerned (with)

carefree; apathetic

that could not have been imagined

accidental

having no use; not able to do what is intended; having no result

not working; not valuable