Etymology a-lert-ness n 1: the state of being watchful and prompt to meet danger or an emergency 2: being quick to perceive and act 3: being in a state of readiness. In sixteenth-century Italy, the military call, “Alla erta!” meant “To the lookout!” The French adapted this command as á l` airte, which later became its own word: allerte. It is from this form that the English word alert is derived.