Why is it "let" and not "net"?
Seems like a random thing to call it though – why not "table" or "apple" – why "let"?
I'm not too sure of this. I remember reading somewhere(don't remember the source) that the term let comes from the french word for net, filet (fillet?). Initially it was only for serves that hit the net and landed inside. Later it was expanded to include more things like niff mentions(I am guessing this was done just so that another term need not be introduced