admonish, admonition - ad-MOH-nih-SHUN - warning, seriously advising
Example: "Today the NY Times offered this admonition: 'A lot of time we are chasing shadows, but it's better to do that than find out later you let something get by.'"
As a starter: and as a former teacher in English, I hope to add to reader's vocabulary by presenting a word a day in simple terms that anyone can understand - from current use in publications, radio,TV, etc. Remember: use a new word three times in a day and it's yours forever!