WHISTLER

[whis.tler] n (bef. 12c): one that whistles: as a: any of various birds; esp: any of numerous Australian and Polynesian oscine birds (esp. genus Pachycephala) that are related to the shrikes and have a whistling call b: a large mountain marmot (Marmota caligata) of northwestern No. America c: a broken-winded horse d: a very-low-frequency radio signal that is generated by lightning discharge, travels along the earth's magnetic-field lines, and produces a sound resembling a whistle of descending pitch in radio receivers