noun (n)

• expandable metal or wooden wedge used by printers to lock up a form within a chase(noun.artifact)

  Synonym:
  coign, quoin
  

  source: wordnet30
• the keystone of an arch(noun.artifact)

  source: wordnet30
• A quoin.(noun)

  source: webster1913
• The practice of quartering one's self as landlord on a tenant; a quartering of one's self on anybody.(noun)

  source: webster1913