Alert

You should be alert to the possible dangers.

We must be alert to dangers.

The climber stayed alert while climbing the precipice.

I feel more alert after drinking a cup of coffee.

My watchdog is alert to the slightest sound and movement.

500 policemen were put on strict alert.

The alert guard perceived a dim shape in the distance.

The alert officer perceived a dim shape in the distance.

Be alert when you cross a busy street!

The hunter was alert to every sound and movement.