Definition of whistler
: one that whistles: such as
a
: any of various birds;
especially
: any of numerous oscine birds (especially genus Pachycephala) found chiefly in Australia and South Pacific islands and having a whistling call
b
: a large marmot (Marmota caligata) of northwestern North America having a shrill alarm call
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
