#worm.screw  screw thread on a gear with the teeth of a worm wheel or rack
  supertype:  screw  a fastener with a tapered threaded shank and a slotted head
  part of:  worm_gear  gear consisting of a shaft with screw thread (the worm) that meshes with a toothed wheel (the worm wheel); changes the direction of the axis of rotary motion

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