防禦式設計又叫做防守設計，係喺專案設計階段諗嘅應急方案。防禦式設計係諗住用家可能會用得唔啱嘅所有情況，用設計手法避免唔啱嘅用法，抑或降低錯誤使用嘅機會。譬如話某隻插頭需要以特定嘅方向插入插蘇度，而且呢個好重要，設計師就要諗辦法設計呢個插頭，令佢必須嚮正確嘅方向先插到入去。電源插頭大多會噉樣設計，避免火線同中心線插反。
Defensive design, also known as defensive design, is an emergency plan that is thought of in the project design stage. Defensive design is about preparing for all situations where the user might use it incorrectly, and using design techniques to avoid the wrong use or reduce the chance of using it incorrectly. For example, if a plug needs to be inserted in a specific direction, and this is very important, the designer has to find a way to design the plug so that it must be inserted in the right direction. Most power plugs are designed in this way to avoid the live wire and center wire being reversed.