Whistler \Whis"tler\, n. [AS. hwistlere.] 1. One who, or that which, whistles, or produces or a whistling sound. 2. (Zo["o]l.) (a) The ring ousel. (b) The widgeon. [Prov. Eng.] (c) The golden-eye. (d) The golden plover and the gray plover. 3. (Zo["o]l.) The hoary, or northern, marmot ({Arctomys pruinosus}). 4. (Zo["o]l.) The whistlefish.