With afterwards shortening with the vowel. The indicating "a divide of land" (perception 2), attested previously in watershed (18th century) seems for being an outgrowth of previously physical senses on the term, as "the A part of a person's hair" or "a passageway in between the threads of a warp https://electricbikehoist43208.wikipublicity.com/5456205/what_does_sheds_mean