公告
gōnggào · HSK 5
placard
📢 公 = public + 告 = tell/announce
公 means public/official and 告 means to tell or notify, so 公告 literally is a public notice — a formal announcement or placard issued to everyone.
公 — eight 八 + private 厶
Originally an ideograph showing 八 (to divide) over 厶 (private/self), depicting the act of splitting away from selfish interest. The combination came to mean 'public' or 'fair,' the opposite of private. It later extended to senses like 'duke,' 'lord,' and 'grandfather.'
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).