When you are alert, you are aware and ready to react in a hurry. You are on your guard, and you are ready to fight or run if necessary.

  • He always seems to be alert, even in the middle of the night.

  • Being alert is important because you never know when the danger will come.

Definition of alertness


a state of readiness to respond




the process of paying close and continuous attention


vigilance, wakefulness, watchfulness


lively attentiveness


on the qui vive, sharp-sightedness

Nearby Words

alertness Pronunciation in a video (3)

Example Sentences for alertness

  • 1

    Teaching is directed towards developing mental alertness of the candidates.

  • 2

    The milkmaid sends an alert.

  • 3

    I will alert the creator of the map.

  • 4

    He alerts the authorities to the secret.

  • 5

    The board alerted the Emperor to the event.

  • 6

    The brothers escape and alert the police.

  • 7

    The centurion alerted the Emperor to the event.

  • 8

    The girl escapes and alerts the police.

  • 9

    The rooster is a symbol for watchfulness and alertness.

  • 10

    After the millennium alert, the government relaxed.