effective Antonyms

ineffective potential vain useless unwieldy unsuccessful unreal unorganized unfruitful valueless void unprofitable unsystematic unimportant worthless weak wasteful voidable voided uncapable timid rewardless resultless reputed pyrrhic purposeless purportless profitless powerless sapless senseless thankless supposed successless sterile sleeveless slavish sisyphean sinful unavailing junky time-consuming self-defeating verboten self-effacing null and void unproductive counterproductive against the law trancelike