Английский Этимологический словарь - whistle (v.)

- O.E. hwistlian, from P.Gmc. *khwis-, of imitative origin; the noun is from O.E. hwistle. Used also in M.E. of the hissing of serpents. To wet one's whistle (14c.) may originally have refered to pipes. To whistle for (with small prospect of getting) is probably from nautical whistling for a wind. Figurative use of whistle-blower first attested 1970. To whistle "Dixie" is from 1940.