The spiral groove around the shaft of a screw is called the

The spiral groove around the shaft of a screw is referred to as the thread. The threads are essentially the helical ridges that allow screws to engage with materials when they are turned. The function of the thread is crucial in converting rotational motion into linear motion, which is why screws are effective when they need to hold or fasten objects together securely.

Understanding threads is fundamental in various mechanical applications. They dictate how far a screw will penetrate into a material for every rotation, which is often defined by the pitch. However, pitch refers specifically to the distance between successive threads, not the thread itself.

The other options do not accurately describe this feature of a screw. A kerf typically refers to the width of a cut made by a saw, and a slot is generally a long, narrow opening or groove, neither of which applies to the spiral structure of a screw. The term "thread" captures the defining characteristic of the screw's design that contributes to its mechanical advantage.