(usually followed by `to') showing acute awareness; mentally perceptive; "alert to the problems"; "alive to what is going on"; "awake to the dangers of her situation"; "was now awake to the reality of his predicament"
If you alert someone to a situation, especially a dangerous or unpleasant situation, you tell them about it. He wanted to alert people to the activities of the group I was hoping he'd alert the police. see also red alert
An alarm from a real or threatened attack; a sudden attack; also, a bugle sound to give warning
If you are alert to something, you are fully aware of it. The bank is alert to the danger
a warning serves to make you more alert to danger condition of heightened watchfulness or preparation for action; "bombers were put on alert during the crisis"
An alert is a situation in which people prepare themselves for something dangerous that might happen soon. Due to a security alert, this train will not be stopping at Oxford Circus
very attentive or observant; "an alert and responsive baby is a joy"; "caught by a couple of alert cops"; "alert enough to spot the opportunity when it came"; "constantly alert and vigilant, like a sentinel on duty"