'闹钟' literally combines '闹' (nào), meaning 'to make noise' or 'to disturb', and '钟' (zhōng), meaning 'clock'. Together, they form a compound noun meaning 'alarm clock' — a device that makes noise at a preset time to wake someone up or signal an event. The character '闹' emphasizes the audible, attention-grabbing function, while '钟' specifies the timekeeping nature of the object.

This word is used daily in contexts involving schedules, waking up, reminders, or time management. It’s neutral in register — appropriate for spoken and written Chinese across ages and settings. You’ll commonly see it in phrases like '设闹钟' (set an alarm), '关闹钟' (turn off the alarm), or '闹钟响了' (the alarm went off). Unlike more technical terms like '电子钟' (digital clock), '闹钟' specifically implies an alarm function, whether mechanical, digital, or app-based.