警告 (jǐnggào) means 'warning' — a formal or serious notice intended to alert someone to danger, risk, or unacceptable behavior. The first character 警 (jǐng) means 'to be on guard' or 'alert', and the second character 告 (gào) means 'to tell' or 'to inform'. Together, they convey the idea of 'telling someone to be cautious'. It’s commonly used in official, medical, legal, or safety contexts — such as warning labels on medicine, traffic signs, or disciplinary notices at work or school.

This word carries moderate formality and gravity; it’s stronger than 提醒 (tígǐng, 'reminder') but less severe than 处罚 (chǔfá, 'punishment'). It can function as both a noun ('a warning') and a verb ('to warn'), often followed by an object or clause introduced by 'that' or 'about'. In spoken Chinese, it’s more frequent in written or institutional settings than in casual conversation.