Other forms: mushers
A musher is someone who rides in a sled behind a team of sled dogs. To be a musher, you need (among other things) to learn commands and dress warmly.
The sport of driving a team of dogs is known as mushing, and a person who participates is a musher. Both terms come from the command "Mush!" that mushers have traditionally called to urge the sled dogs forward. In the late 1860s, this term was recorded as mouche, which likely comes from the French marche, "go" or "run." Today, even more confusingly, mushers are more likely to say "Hike!" than "Mush!"