A hook-shapped attachment for an earring that sits behind the earlobe and tightens with a screw. Also, an earring that uses this type of attachment.
A mechanism for attaching a small item to clothing that operates by a post which goes through the cloth and a small backing plate that screws to the post. Also, the medal, tie pin, button, etc. that uses this type of attachment.
A type of case for a pocket watch where the mechanism is accessed by a removable back plate that screws onto the back of the case. Also, a watch that has such a case.
An industrial digging machine that uses a large screw at the back to drill into the ground.
A type of propeller in which the blades are angled to produce a motion similar to threading a screw. Also, the angle of the blades on such a propeller.