按钮 (àn niǔ) literally combines 按 (àn), meaning 'to press' or 'to push', and 钮 (niǔ), meaning 'knob' or 'buckle'. Together, they refer specifically to a physical or digital control interface element designed to be pressed — like the round or rectangular switches on appliances, remote controls, keyboards, or software interfaces. It is a countable noun and commonly appears in both hardware and UI contexts.

This word is neutral in register and widely used in everyday life — from household devices (e.g., microwave buttons) to mobile apps (e.g., 'submit button'). Unlike the more general term 键 (jiàn, 'key'), which often refers to keyboard keys, 按钮 emphasizes function: pressing to trigger an action. It rarely appears in compound words without its core meaning intact — for example, 删除按钮 (shānchú àn niǔ, 'delete button') clearly signals an actionable control.