warning whistle
- alarmUrgent warning signal
- alertWarning or watchfulness
- sirenWailing alert device
- signalMessage-conveying cue
- shrillHigh-pitched and harsh
blow · referee · train · kettle · steam · piercing · sharp · danger · caution · tweet · blast · emergency · lifeguard · coach · foul · attention · shriek · loud
- whistlespea whistle, tin whistle, penny whistle, police whistle, referee whistle
temporal direction
warning whistlestarting signal
Cue to begin
start signal · opening bell · starter's pistol · green flag · play ball