1) Cardboard 2) Cheap 3) Cheesy 4) Chintzy 5) Crummy 6) Delicate 7) Fallacious 8) Frail 9) Insubstantial 10) Lame 11) Light 12) Onionskin 13) Papery 14) Punk 15) Sleazy 16) Slight 17) Tenuous 18) Thin 19) Tinny 20) Weak 21) Weightless 1) Delicate 2) Fragile 3) Frail 4) Insubstantial 5) Lacking solidity or strength 6) Lacking strength 7) Lame 8) Light 9) Light and thin 10) Like tissue paper 11) Liquid container 12) Not believable 13) Not convincing 14) Not sturdily built 15) Not very sturdy 16) Poorly supported 17) Slight 18) Slang for banknote 
• (superl.) Weak; feeble; limp; slight; vain; without strength or solidity; of loose and unsubstantial structure; without reason or plausibility; as, a flimsy argument, excuse, objection. • (n.) A bank note. • (n.) Thin or transfer paper.
Flim'sy adjective [ Compar. Flimsier ; superl. Flimsiest .] [ Confer W. llymsi naked, bare, empty, sluggish, spiritless. Confer Limsy .] Weak; feeble; limp; slight; vain; without strength or solidity; of loose and unsubstantia...Flim'sy noun 1. Thin or transfer paper. 2. A bank note. [ Slang, Eng.]
Flimsy is slang for a banknote.
[adj] - very thin and insubstantial 2. [adj] - lacking solidity or strength 3. [adj] - having little substance or significance
tenuous adjective having little substance or significance; `a flimsy excuse`; `slight evidence`; `a tenuous argument`; `a thin plot`light adjective very thin and insubstantial; `thin paper`; `flimsy voile`; `light summer dresses`
lacking solidity or strength