What does Shed mean?
The opening formed by raising and lowering the yarns on a during the weaving process. The shed opening is what the yarns are passed through to complete the weaving interlace.
Style Terms explains Shed
The shed is the (temporary) area of space between the upper and lower yarns on a that the shuttle passes through.
A shedding device separates the yarns and alternatively raises and lowers them in order to simplify the weaving process for the weaver so that he/she doesn’t have to individually thread the shuttle through alternating threads.