having little substance or significance; "a flimsy excuse"; "slight evidence"; "a tenuous argument"; "a thin plot" lacking solidity or strength; "a flimsy table"; "flimsy construction"; "a fragile link with the past" very thin and insubstantial; "thin paper"; "flimsy voile"; "light summer dresses
If you describe something such as evidence or an excuse as flimsy, you mean that it is not very good or convincing. The charges were based on very flimsy evidence. = weak, unconvincing
Weak; feeble; limp; slight; vain; without strength or solidity; of loose and unsubstantial structure; without reason or plausibility; as, a flimsy argument, excuse, objection