Made stiff or reinforced with buckram, a stiff fabric used to give structure to garments or other materials.
From 'buckram' (a coarse, heavily starched fabric) plus the past participle suffix '-ed'. Buckram itself comes from Bukhara, the Central Asian city famous for producing quality cloth.
Your grandmother's stiff petticoats or the structured collars in vintage photos were likely buckramed—that fabric was the original fashion technology for keeping clothes in perfect shape without modern synthetic stiffeners!
Complete word intelligence in one call. Free tier — 50 lookups/day.