35 synonyms for ineffective such as failed, abortive, and bootless. Ineffective is an adjective, and its antonyms are effective and efficient.
Abortive, bootless, failed, feeble, fruitless, futile, hopeless, idle, impotent, inadequate, incapable, incompetent, ineffectual, inefficacious, inefficient, inept, inutile, lame, non-successful, poor, powerless, profitless, purposeless, to no effect, unavailing, unfit, unfructuous, unproductive, unprofitable, unsuccessful, useless, vain, weak, and worthless.