a screw having a ring-shaped head.
a wood screw with its shank bent into a ring
noun 1. screwworm fly.
noun 1. the head or top of a screw having a slot for the end of a screwdriver. screwball 1
noun 1. a hook having a shank in the form of a screw.
noun 1. jackscrew. noun 1. a lifting device utilizing the mechanical advantage of a screw thread, the effort being applied through a bevel drive Also called jackscrew, jack