- futile, ineffectual, otiose, unavailing - producing no result or effect; "a futile effort"; "the therapy was ineffectual"; "an otiose undertaking"; "an unavailing attempt"
Antonyms: useful, utile (indirect, via useless)
- bootless, fruitless, futile, sleeveless, vain - unproductive of success; "a fruitless search"; "futile years after her artistic peak"; "a sleeveless errand"; "a vain attempt"
Antonym: productive (indirect, via unproductive)