warning signal
Alert before trouble
A warning signal is any indicator that alerts to potential danger, problems, or the need for caution.
It can be literal—a siren, flashing light, or alarm—or figurative: The sudden drop in sales was a warning signal that something was wrong.
In biology, warning signals are colors or patterns that advertise an organism's toxicity to predators.
- buzzerElectric signaling device
- sirenWailing alert device
- error messageSoftware's complaint about problems
- alarmUrgent warning signal
- cry for helpUrgent request for assistance
whistle · alert · notification · check engine light · omen · harbinger · trembling · flag · pacing · flashing light · horn · klaxon · beacon · bell · storm clouds · heads-up · shot across the bow · emergency broadcast
- dangersdanger, peril, hazard, risk, menace
- soundssound, beeps, listen, sounds, hear
- signalswaved, nodded, gestured, blinked, flashed
- Warning Systemsalarm, alarms, alert system, sirens, fire alarm
- rail safetytrain stop, crossing arms, safety gates, railroad crossing, train control
- signal lightsbeacon, beacon light, navigation light, emergency beacon, locator beacon
warning signalall-clear
Signal danger has passed
green light · stand-down · reassurance · cancellation notice · false alarm
warning signalinvitation
Request to attend
welcome sign · enticement · lure · attractant · come-hither
warning signalgreen light
Authorization to proceed
start signal · go-ahead · invitation · welcome sign · beckoning
sign, warn, warning, signal, warned, signals, warnings, signaling, forewarn