Noun
constrictor knot (plural constrictor knots)
A type of knot or hitch often used to fasten the neck of a sack of grain or flour. This knot has diverse practical applications as it is very stable and can be difficult to release.
The following 3 knots do not fit the simple "two crossing turns - ends tucked under" definition but are very secure: * A slipped Constrictor knot where the ends are passed through the opposing slips for security is quite secure as a bag knot. Source: Internet