(of an action) of no use; having no effect

hopeless, pointless

doing no work; not active or in use; to spend (time) in a lazy manner

worthless, ineffective

not producing the effect(s) desired

useless

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

weak, useless

not working; not valuable

not working; not valuable

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

not working; not valuable