the.com/constrictor knot

means A simple, extremely tight-binding knot used to clamp a rope or bundle firmly onto something — the harder you pull, the more it digs in, and it's often meant to be cut off rather than untied.

from The knot itself is old and widely known among sailors and riggers as a cousin of the clove hitch, with an extra tucked turn that locks it down. The modern name 'constrictor knot' is generally credited to early 20th-century knot cataloguers, notably the knot-tying authority Clifford Ashley, who gave it that name for its snake-like grip — a nod to constrictor snakes that tighten around prey rather than striking. Before being formally named and classified, the same binding appears to have been used instinctively by workers and sailors for centuries under no fixed name at all.