noun (n)

• two items of the same kind(noun.quantity)

  Synonym:
  brace, couple, couplet, distich, duad, duet, dyad, pair, span, twain, twosome, yoke
  

  source: wordnet30
• two performers or singers who perform together(noun.group)

  Synonym:
  duet, duette
  

  source: wordnet30
• a pair who associate with one another(noun.group)

  Synonym:
  couple, duet, twosome
  

  source: wordnet30
• a musical composition for two performers(noun.communication)

  source: wordnet30
• A composition for two performers; a duet.(noun)

  source: webster1913