whistle

noun

1.
the sound made by something moving rapidly or by steam coming out of a small aperture
Derived from:
whistle
2.
the act of signalling (e.g., summoning) by whistling or blowing a whistle
Derived from:
whistle
3.
a small wind instrument that produces a whistling sound by blowing into it
4.
acoustic device that forces air or steam against an edge or into a cavity and so produces a loud shrill sound
5.
an inexpensive fipple flute