a device in which the forcible passage of air, steam, the breath, etc through a slit or against a thin edge in a short tube produces a loud high-pitched sound
a shrill clear sound produced by or as if by a whistle
the whistle of the wind
blow the whistle on
informal to report (a person acting wrongly or a wrong act) to an authority or person with responsibility
[with allusion to blowing a whistle as a signal to end an activity, especially by a sports referee to stop play in a game.]clean as a whistle
absolutely clean or perfectly clear
[Old English hwistle]