- a person or thing that whistles.
- something that makes a sound like a whistle: The windstorm was a 60-mile-an-hour whistler.
- any of various birds whose wings whistle in flight, especially the goldeneye.
- thickhead(def 2).
- a large marmot, Marmota caligata, of mountainous northwestern North America, closely related to the woodchuck.
- a horse afflicted with whistling.
- Radio. a whistling sound heard on a radio, a type of interference caused by distant lightning.