Nouns

(n)onionskin, flimsya thin strong lightweight translucent paper used especially for making carbon copies

Adjectives

(s)flimsy, insubstantiallacking solidity or strength“a flimsy table”, “flimsy construction”, “vinyl siding has become the standard-bearer for cheap, insubstantial construction”
(a)unconvincing, flimsynot convincing“a flimsy argument”, “as unconvincing as a forced smile”
(s)flimsy, fragile, slight, tenuous, thinlacking substance or significance“slight evidence”, “a tenuous argument”, “a thin plot”, “a fragile claim to fame”