What does the word warning mean?

Usage examples for warning

  1. But they'll give warning of our having been there on our way to Mafeking. – A Dash from Diamond City by George Manville Fenn
  2. Even Ben was shocked by this warning. – Somewhere in Red Gap by Harry Leon Wilson
  3. Care should be taken to avoid tea or coffee, and I think a word of warning ought to go forth against milk. – Methods of Authors by Hugo Erichsen