The term design debt refers to how much is the debt that you incur everytime you avoid doing the right thing (like refactoring, removing duplication/redundancy) letting the code quality deteriorate over time.
The term "design debt" was coined by Ward Cunningham to describe the obligation that a software organization incurs when it chooses a design or construction approach that's expedient in the short term but that increases complexity and is more costly in the long term.
