'辩护' (biàn hù) literally combines '辩' (to argue, debate) and '护' (to protect, defend), forming a compound meaning 'to defend'—especially in formal, legal contexts. It refers to the act of presenting arguments or evidence to support someone accused of wrongdoing, most commonly performed by a lawyer on behalf of a client in court. While it can occasionally appear in non-legal discussions (e.g., defending an idea), its primary and most natural usage is within the justice system.

The word functions as both a noun ('a defense') and a verb ('to defend'). As a noun, it often appears after classifiers like '一次' (once) or '律师的' (the lawyer’s); as a verb, it usually takes a direct object (e.g., '为被告辩护' — 'defend the defendant'). It carries a formal, professional tone and is rarely used in casual speech or emotional arguments among friends.