Definition of mushers:
(n) :
One who drives a dogsled over ice and snow; specifically, one who participates in a dogsled race.
(n) :
One who travels over snow, chiefly by dogsled but also by foot.
(n) :
(chiefly London, slang) Synonym of mush (“a cab driver who is the owner of their cab, and sometimes a small number of other cabs as well”).
(n) :
(England, dialectal, chiefly Hampshire) A mushroom.