flim·sy / ˈflimzē/ • adj. (-si·er, -si·est) comparatively light and insubstantial; easily damaged: voyagers who crossed the sea in flimsy boats. ∎ (of clothing) light and thin: I wore flimsy clothes and needed warming. ∎ (of a pretext or account) weak and unconvincing: a pretty flimsy excuse.• n. (pl. -sies) Brit. a document, esp. a copy, made on very thin paper: credit-card flimsies. ∎ very thin paper: sheets of yellow flimsy.DERIVATIVES: flim·si·ly / ˈflimzəlē/ adv.flim·si·ness / -zēnis/ n.