(s)futile, ineffectual, otiose, unavailing, meaninglessproducing no result or effect“a futile effort”, “the therapy was ineffectual”, “an otiose undertaking”, “an unavailing attempt”
(s)bootless, fruitless, futile, sleeveless, vainunproductive of success“a fruitless search”, “futile years after her artistic peak”, “a sleeveless errand”, “a vain attempt”