alert

Universal Words adjective, verb, noun adjective 1 able to think quickly; quick to notice things: Suddenly he found himself awake and fully alert. * Two alert scientists spotted the mistake. * Try to stay alert while driving at night. * an alert mind * mentally alert 2 ~ to sth aware of sth, especially a problem or danger: We must be alert to the possibility of danger. * She was alert to the slightest sound. alertly adjective alertness noun [U] verb [oftenpassive] 1 to warn sb about a dangerous or urgent situation: [VN] Neighbours quickly alerted the emergency services. * Alerted by a noise downstairs, he sat up and turned on the light. [also VN(that), VNtoinf] 2 [VN] ~ sb to sth to make sb aware of sth: They had been alerted to the possibility of further price rises. noun 1 [sing.,U] a situation in which people are watching for danger and ready to deal with it: Police are warning the public to be on the alert for suspicious packages. * More than 5000 troops have been placed on (full) alert. 2 [C] a warning of danger or of a problem: a bomb / fire alert seealsoREDALERT