whistle

A whistle is a sound like music. A person makes a whistling sound by blowing air when the person's mouth is in a little circle.

Example: The whistle of the wind in trees was low and sad.

A whistle is a little instrument made of wood, metal or other material. A person puts the instrument in the person's mouth and blows air to make a loud whistling sound.

Example: When you are in danger, blow your whistle loudly and someone will run and help you.

To whistle is to make a whistling sound with one's mouth.

Example: A happy person is able to whistle and work at the same time.