hiker n.

1908, agent noun from hike (v.). Earlier as a type of boat:

The "hiker" or "tuck-up" as it is more generally termed, is a craft peculiar to the Delaware River, and is to the youth residing along the banks of that stream what the racing shell is to the Torontonian .... The origin of the name "hiker" is veiled in mystery. No member of the clubs engaged in sailing these boats can give anything like a satisfactory derivation of the word. The most common explanation is that it is corrupted from the local verb "to hike," which means to run or fly swiftly. ["Harper's Young People," 1885]