警告
けいこく · keikoku · JLPT N3 · noun
warning
🚨 警告 = alert + tell: you are alerted and told, so it is a warning
警 means to alert or guard (as in 警察 keisatsu, police) and 告 means to tell or announce (as in 報告 hōkoku, report). Telling someone to be on alert is a warning. Sound hook: kei-koku sounds like cake cook, who warns that the oven is hot.
告 — ox 牛 (top) + mouth 口
Originally a pictograph showing an ox with something on its head, possibly a yoke or sacrificial marker, combined with 口 (mouth) to suggest announcing or reporting. The character came to mean 'to tell' or 'to announce,' as in making a formal declaration. Today it commonly appears in words like 告诉 (to tell) and 报告 (report).