Definition of useless :
Having, or being of, no use; unserviceable; producing no good end; answering no valuable purpose; not advancing the end proposed; unprofitable; ineffectual; as, a useless garment; useless pity.
unsatisfying, null, trifling, shadowy, junked, thrive, cast-off, profitless, worthless, unsubstantial, hopeless, inutile, waste, otiose, inefficient, unimportant, impracticable, nugatory, unavailing, efficient, vapid, incompetent, empty, inoperative, barren, used, trivial, deceitful, delusive, unnegotiable, inconstant, baseless, unhelpful, idle, unprofitable, discarded, usable, broken, visionary, inefficacious, unuseable, unreal, scrap, bootless, affect
unsuccessful (part of speech: adjective)
useless (part of speech: adjective)