the world > action or operation > safety > protection or defence > vigilance > be vigilant or on one's guard [verb (intransitive)] > take warning (2)
to take warning: to alter one's course of action when warned of its danger. Const. by (another's ill-fortune, etc.).
A warning of danger, esp. one intended to startle or rouse the previously unwary into action. Frequently in to give (also take, raise) the alarm.