a small wind instrument that produces a whistling sound by blowing into it
"The children played their plastic whistles during the recess game."
acoustic device that forces air or steam against an edge or into a cavity and so produces a loud shrill sound
"The train engineer sounded the whistle to warn passengers as the station came into view."
an inexpensive fipple flute
"The school children blew into their cheap plastic whistles to signal the end of recess."
A device designed to be placed in the mouth and blown, or driven by steam or some other mechanism, to make a whistling sound.
"The referee blew his whistle to signal the start of the game."
In plain English: A whistle is an object that makes a high-pitched squeaking sound when you blow air through it.
"The referee blew his whistle to signal that play had stopped."
Usage: The noun form refers specifically to the physical instrument that produces the sound, whereas the verb describes the act of making that noise. Avoid using "whistle" as a synonym for any shrill sound; it must be caused by air passing through a specific restriction or device.
To make a shrill, high-pitched sound by forcing air through the mouth. To produce a whistling sound, restrictions to the flow of air are created using the teeth, tongue and lips.
"He tilted his head back and used his fingers to direct the wind across his top lip so he could whistle a clear tune."
In plain English: To whistle is to make a high-pitched sound by blowing air through your lips while shaping them into an opening.
"He whistled a happy tune while walking down the street."
The word "whistle" comes from the Middle English whistle, which was borrowed from the Old English verb hwistle. Originally, it referred to the act of producing a high-pitched sound by blowing air through pursed lips or an instrument.