flimsy

(noun) a thin strong lightweight translucent paper used especially for making carbon copies. Synonyms: onionskin.

(adj) lacking solidity or strength. Examples: "A flimsy table." "Flimsy construction."

(adj) not convincing. Synonyms: unconvincing (vs. convincing). Examples: "Unconvincing argument." "As unconvincing as a forced smile."

(adj) lacking substance or significance. Synonyms: fragile, slight, tenuous, thin. Examples: "Slight evidence." "A tenuous argument." "A thin plot"; a fragile claim to fame."