A knotted "eye" of cord, corresponding to the "taches" or knobs in the edges of the curtains of the tabernacle, for joining them into a continuous circuit, fifty to a curtain (Exodus 26:4,5,10,11).
These dictionary topics are from M.G. Easton M.A., D.D., Illustrated Bible Dictionary, Third Edition, published by Thomas Nelson, 1897. Public Domain, copy freely.
Easton, Matthew George. "Entry for 'Loop'". "Easton's Bible Dictionary".