• noun:   a warning serves to make you more alert to danger
• noun:   condition of heightened watchfulness or preparation for action

  Example: "Bombers were put on alert during the crisis"

• noun:   an automatic signal (usually a sound) warning of danger
• verb:   warn or arouse to a sense of danger or call to a state of preparedness

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

• adjective:   mentally responsive

  Example: "An alert mind"

• adjective:   very attentive or observant

  Example: "An alert and responsive baby is a joy"

• adjective:   (usually followed by `to') showing acute awareness; mentally perceptive

  Example: "Alert to the problems"

• adjective:   not unconscious; especially having become conscious

  Example: "The patient is now awake and alert"

• name:  A surname (very rare: popularity rank in the U.S.: #66111)

Related words...