dou·blure \ˌdəˈblu̇(ə)r, düˈ-\noun (-s) Etymology: French, from Middle French, lining of a garment, from doubler to line, double + -ure — more at double 1.: the lining of a book cover; especially: an ornamental lining (as of tooled leather, painted vellum, or rich brocade) 2.: the reflexed margin of a trilobite's carapace