a small object that produces a high whistling sound when you blow into it:
The lifeguard blew his whistle.
a high sound made by blowing a whistle, by blowing air out through your lips, or when air or steam is forced through a small opening:
Larsson scored just minutes before the final whistle.
a piece of equipment on a train or boat that makes a high noise when air is forced through it
the sound of something moving quickly through the air
We could hear the whistle of the jets as they passed overhead.