What is the term for a fastener that features a helical ridge?

The correct term for a fastener that features a helical ridge is indeed a threaded fastener. This type of fastener is characterized by its spiral threads that allow it to be securely fastened into materials, creating a strong connection. The helical ridge helps in converting rotational motion into linear motion, which is essential for tightening or loosening the fastener in applications such as screws and bolts. This thread design enhances the grip of the fastener in the substrate, providing stability and resistance to being pulled out.

While a screw fastener is closely related and also utilizes a helical ridge, the term "threaded fastener" encompasses a broader category that includes various types of fasteners with threads, such as bolts and screws. Thus, while both options can be relevant to the context, the more general term accurately describes any fastener featuring a helical ridge.