1alert 
/əˈlɚt/ adjective
/əˈlɚt/ adjective [more alert; most alert] : able to think clearly and to notice things
▪ An alert guard stopped the robbers. ▪ The nurse kept/stayed alert for any change [=watched for any change] in the patient's condition. ▪ He was tired and had trouble staying alert while he was driving. ▪ She wasn't mentally alert enough to answer the questions. ▪ an alert mind ▪ An alert watchdog guarded the door. — often + to ▪ The nurse should be alert to any change in the patient's condition. ▪ He is alert to [=aware of] his duties as a father.
▪ An alert guard stopped the robbers. ▪ The nurse kept/stayed alert for any change [=watched for any change] in the patient's condition. ▪ He was tired and had trouble staying alert while he was driving. ▪ She wasn't mentally alert enough to answer the questions. ▪ an alert mind ▪ An alert watchdog guarded the door. — often + to ▪ The nurse should be alert to any change in the patient's condition. ▪ He is alert to [=aware of] his duties as a father.
— alert·ly adverb
▪ A watchdog alertly guarded the door.
▪ A watchdog alertly guarded the door.
— alert·ness noun [noncount]
