The oracle-bone form of 告 shows an ox head (牛 niú) above a mouth (口 kǒu). The classical interpretation: when a man presents an ox as a ritual offering or gift to a superior — a lord, an ancestor, the spirits — he simultaneously speaks the reason for the offering. The speaking that accompanies a solemn presentation is 告: to announce, to declare, to make known to a person of higher standing.

This origin explains why 告 carries a strong sense of directionality — the communication flows upward or outward with authority. You 告 a superior, an official, a court, or the public. It is not casual speech but announced speech: a report filed, a charge leveled, a warning issued, an advertisement placed.

To tell / inform (告诉). The everyday sense: 告诉我 (tell me), 告诉他你的想法 (tell him what you think). 告诉 gàosu is among the first verbs learners encounter.

To announce / notify (通告, 公告). Official, public-facing declarations: 公告 (public announcement), 通告 (circular notice), 布告 (posted notice). The register is formal — these appear on walls, in government documents, on websites.

To accuse / sue (控告, 告状). The legal register traces directly to the ritual origin: presenting a grievance to a superior for judgment. 告状 literally means "to file a complaint-shape" — to bring a case.

To warn (警告). 警 (vigilance) + 告 (announce) = to announce vigilance. Used for everything from traffic signs to diplomatic warnings.

To bid farewell (告别). 告别 gào bié — to formally announce a parting. The formality of 告 makes this more ceremonial than 再见.