#head.projection  a projection out from one end; "the head of the nail", "a pinhead is the head of a pin"
  supertype:  #projection  any structure that branches out from a central support
  subtype:  #pinhead  the head of a pin
  part of:  #bolt.screw  a screw that screws into a nut to form a fastener
     part of:  #nut_and_bolt__nutandbolt  a fastener made by screwing a nut onto a threaded bolt
  part of:  #nail  a thin pointed piece of metal that is hammered into materials as a fastener
  part of:  #pin  a small slender (often pointed) piece of wood or metal used to support or fasten or attach things
  part of:  #screw  a fastener with a tapered threaded shank and a slotted head

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