English to English

noun (n)

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

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

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

  Example:
  An inseparable twosome.
  

  Synonym:
  couple, duet, duo
  

  source: wordnet30