adj. 25B6; adjective
the item was worthless : VALUELESS; poor quality, inferior, second-rate, low-grade, cheap, shoddy, tawdry; informal crummy, rubbishy, ten a penny; Brit. informal twopenny-halfpenny; N. Amer. informal nickel-and-dime.
your conclusions are worthless : USELESS, no use, ineffective, ineffectual, fruitless, unproductive, unavailing, pointless, nugatory, valueless, inadequate, deficient, meaningless, senseless, insubstantial, empty, hollow, trifling, petty, inconsequential, lame, paltry, pathetic; informal a dead loss.
his worthless son : GOOD-FOR-NOTHING, ne'er-do-well, useless, despicable, contemptible, low, ignominious, corrupt, villainous, degenerate, shiftless, feckless; informal no-good, lousy.
valuable, useful.