The verb admonish is used to indicate someone did something wrong or against his duties and obligations. It is also used to give friendly advice or warning.
Synonyms are chide, rebuke, scold or warn.
The word origins from Vulgar Latin (mid. 14th century) amonesten meaning “remind, urge, exhort, warn, give warning” and admonere “bring to mind, remind (of a debt)”. The “d” in the word came from the Modern French admonester. The part monēre relates from English to monitor, monitory or “giving a warning”.
They were first admonished before they had to leave the room.
Before they went into the forest alone he admonished them to be careful.
The sign admonished to “mind the gap”.