(a.) Not efficacious; not having power to produce the effect desired; inadequate; incompetent; inefficient; impotent.

barren bootless failed failing fruitless futile gainless immature ineffective ineffectual inefficacious lame manque miscarried miscarrying nonremunerative of no effect otiose profitless rewardless sterile stickit stillborn successless unavailable unavailing unformed unfortunate unmatured unproductive unprofitable unremunerative unrewarding unripe unsuccessful useless vain