What does the term "tendency of a knot under load to change form" refer to?

The term "tendency of a knot under load to change form" specifically refers to slippage. When a knot is subjected to tension, the forces can cause it to shift or change its configuration, which may lead to a decrease in the knot's effectiveness or security in holding load. Slippage occurs when the components of the knot begin to move relative to each other, potentially compromising the knot's integrity.

Understanding slippage is crucial for anyone involved in rigging or hoisting applications because it directly impacts safety. It is important to select the right type of knot for each specific application, ensuring that it will maintain its shape and stay secure under load. Recognizing and addressing potential slippage is vital for ensuring that loads are handled safely and effectively.

The other options, such as deformation, depict different concepts. Deformation refers to the physical changing of materials' shapes due to external forces, which is a broader term that applies to many contexts beyond knots. Loosening describes a situation where the knot becomes less tight without necessarily implying a change in its fundamental configuration. Abrasion generally refers to the wear or damage that occurs due to friction or contact with other materials, which is unrelated to the specific behavior of knots under load.