mid-15c., apparently from in + step, "though this hardly makes sense" [Weekley]. An Old English word for "instep" was fotwelm. Middle English also had a verb instep "to track, trace" (c. 1400).
权威例句
1. The machine apply for leather handbags or instep folding turn edging.
该机适合皮革、皮包、鞋面折边、翻边.
2. Leather upper features straps over the instep for support.
在皮革上的支持脚背功能松紧带.
3. Does urine blister grow on infantile back of hand, instep?
婴儿手背 、 脚背上长小水疱?
4. This machine can mold the joint point and instep point simultaneously.
一次整型动作即可同时完成关节点与脚背点之定型.
5. Attacks to the arms or legs, groin, joints, or instep.