A deleted root in The Etymologies of the 1930s with the gloss “open” and the forms √ED and extended √EDÉR, but it had no derivatives (EtyAC/ED).
Middle Primitive Elvish
lat
root. lie open; be extended, stretch, be situated (of an area)
lath
root. string, thong
pantā
adjective. open
ed(er)
root. open
A root in The Etymologies of the 1930s glossed “string, thong”, with derivatives like ᴹQ. latta “strap” and N. lhath “thong of (?leather)”, the last gloss being somewhat unclear (Ety/LATH).