Alert definition

(1) 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"

(2) (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"

(3) Not unconscious; especially having become conscious

"The patient is now awake and alert"

(4) Mentally responsive

"An alert mind"

(5) An automatic signal (usually a sound) warning of danger

(6) A warning serves to make you more alert to danger

(7) Condition of heightened watchfulness or preparation for action

"Bombers were put on alert during the crisis"

(8) Warn or arouse to a sense of danger or call to a state of preparedness

"The empty house alarmed him"

"We alerted the new neighbors to the high rate of burglaries"