Bowline. A knot formerly used to secure to the cringle on the leach of the sail the 'bowline' that is, the rope which led to the stem and kept the weather leach of the sail taut when sailing on a wind. The bowline is a knot invaluable to sailors, as it is absolutely secure and can generally be easily untied as soon as the strain is to be released. If the strain is to be very great, it is used with a toggle to prevent the knot from jambing. An example of ropework from a collection of demonstration knots.