cuckold's knot

noun Nautical.
  1. a hitch, as for holding a spar, consisting of a single loop with the overlapping parts of the rope seized together.

Origin of cuckold's knot

First recorded in 1840–50; so called because the noose so made is insecure
Also called cuckold's neck, ring seizing, throat seizing.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018