noun (n)

• a connection (like a clamp or vise) between two things so they move together(noun.artifact)

  Synonym:
  yoke
  

  source: wordnet30
• a mechanical device that serves to connect the ends of adjacent objects(noun.artifact)

  Synonym:
  coupler
  

  source: wordnet30
• the act of pairing a male and female for reproductive purposes(noun.act)

  Example:
  The casual couplings of adolescents.
  

  Synonym:
  conjugation, mating, pairing, sexual union, union
  

  source: wordnet30
• The act of bringing or coming together; connection; sexual union.(noun)

  source: webster1913