alerter
One who warns
Alerter is the comparative form of alert, meaning more watchful or attentive: Stay alerter when driving at night.
The word is grammatically correct but uncommon—most speakers prefer "more alert." Alerter also names a person or device that issues alerts: The system's alerter notified staff of the breach.
Urgent warning signal
- sirenWailing alert device
- beaconGuiding light source
- buzzerElectric signaling device
- klaxonElectric warning horn
sensor · detector · monitor · bell · horn · flash · flare · chime
Insider who reports misconduct
- informerOne who reveals secrets
- informantOne who provides intelligence
- tipsterOne who shares predictions
- sourcePoint of origin
leaker · lookout · watchman · sentinel · scout · spotter · observer · reporter
alarm
Urgent warning signal
klaxon · sensor · detector · monitor · bell · horn · flash · flare · chime · whistle
whistleblower
Insider who reports misconduct
- informerOne who reveals secrets
- informantOne who provides intelligence
- tipsterOne who shares predictions
source · leaker · lookout · watchman · sentinel · scout · spotter · observer · reporter · messenger
caution
Careful attention to risk
emergency · advisory · precaution · urgency · imminent · peril · risk · beware · menace · ominous
notification
Formal notice given
ping · prompt · message · toast · banner · badge · chime · vibration · dashboard · webhook
- rail safetycrossing signal, signal light, warning signal, train stop, crossing arms
- train controlsthrottle, brake, emergency brake, reverser, dead man's switch
- spoiler alertCourtesy before plot disclosure
- red alertTop emergency warning state
- stay alertMaintain active awareness
- emergency alertUrgent mass warning notification
- on alert
- weather alertNotice of atmospheric hazards
alert, alertness, alerted, alerting, alerts, hyperalert, unalert