without material strength or solidity

a flimsy fabric; a flimsy structure.

weak; inadequate; not effective or convincing

a flimsy excuse.

a thin kind of paper, esp. for use in making several copies at a time of an article, telegraphic dispatch, or the like, as in newspaper work.

a copy of a report or dispatch on such paper.

adjective

firm , heavy , solid , strong , sturdy , substantial , thick , tough , convincing , plausible , reasonable , serious

adjective

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 , assailable , baseless , contemptible , controvertible , fallacious , false , frivolous , groundless , illogical , improbable , inane , inconceivable , incredible , inept , lame , poor , puerile , thin , trifling , trivial , unbelievable , ungrounded , unpersuasive , unreasonable , unsatisfactory , weakly , wishful , puny , unconceivable , unconvincing , dilapidated , enfeebled , ethereal , gaudy , implausible , ineffective , insignificant , limp , nebulous , shoddy , tenuous