1. a whistler of popular tunes. 2. of the mountains of northwest North America, having a grayish coat and a shrill, whistling cry. 3. Any of various birds that produce a whistling sound. 4. A horse having a respiratory disease characterized by wheezing. 5. An electromagnetic wave of audio frequency produced by atmospheric disturbances such as lightning, having a characteristically decreasing frequency responsible for a whistling sound of descending pitch in detection equipment.
