alert

Awake and paying close attention, ready to notice or respond to something.

• Coffee helps me stay alert.
• The dog remained alert all night.
• She was alert to every small sound.

How to use it: alert to something (Drivers must be alert to sudden changes in traffic.)

Similar words: attentive, watchful, vigilant

Opposites: inattentive, drowsy

Common phrases: stay alert, fully alert, alert to danger

A message that draws your attention to important information or a change.

• My phone showed a news alert.
• You can receive alerts when prices change.
• I turned off email alerts during the meeting.

Similar words: notification, notice

Common phrases: email alert, news alert, receive an alert

A warning that danger or trouble may be near, often given by a sound or signal.

• A fire alert woke us.
• Officials issued an alert about rising river levels.
• The system sounds an alert when smoke appears.

Similar words: warning, alarm

Common phrases: fire alert, sound an alert, flood alert

A state in which military forces are ready to act or fight at short notice.

• The soldiers are on alert.
• Enemy movements prompted a higher state of alert.
• Several aircraft remained on airborne alert overnight.

How to use it: on alert (The troops remained on alert near the border.); put someone on alert (The commander put all units on alert.)

Similar words: readiness

Common phrases: on alert, high alert, airborne alert

To tell someone about a danger, problem, or important fact they need to notice.

• Please alert the police.
• A neighbor alerted us to the fire.
• The app alerts users when their account balance is low.

How to use it: alert someone to something (She alerted us to a problem with the heating.); alert someone that… (The message alerted staff that the building was unsafe.)

Similar words: warn, notify, inform

Common phrases: alert the police, alert someone to, alert staff