producing no result or effect
"a futile effort"
"the therapy was ineffectual"
"an otiose undertaking"
"an unavailing attempt"
unproductive of success
"a fruitless search"
"futile years after her artistic peak"
"a sleeveless errand"
"a vain attempt"
Incapable of producing results; doomed not to be successful; not worth attempting.
"After hours of trying to fix the leaky faucet, I realized my efforts were futile and called a plumber instead."