adjective
not strong; light, thin
Synonyms: chiffon, cut-rate, decrepit, defective, delicate, diaphanous, feeble, fragile, frail, gauzy, gossamer, house of cards, inadequate, infirm, insubstantial, meager, papery, rickety, rinkydink, shaky, shallow, sheer, slapdash, sleazy, slight, superficial, tacky, transparent, unsound, unsubstantial, weak, wobbly
Antonyms: firm, heavy, solid, strong, sturdy, substantial, thick, tough
adjective
unconvincing, implausible
Synonyms: assailable, baseless, contemptible, controvertible, fallacious, false, feeble, frivolous, groundless, illogical, improbable, inadequate, inane, inconceivable, incredible, inept, lame, poor, puerile, superficial, thin, transparent, trifling, trivial, unbelievable, ungrounded, unpersuasive, unreasonable, unsatisfactory, unsubstantial, weak, weakly, wishful
Antonyms: convincing, plausible, reasonable, serious, strong