Definition of "duo"

duo

/ˈdjuː.əʊ/

noun
plural duos
1. Two people who work or collaborate together as partners; especially, those who perform music together.
2. Any pair of two people.
3. Any cocktail consisting of a spirit and a liqueur.
4. A song in two parts; a duet.
  Quotations
  I noticed early on, in playing a duo with a violinist, that when a very cheesy synthesized violin sound plays in counterpoint with a real violin, it can quite convincingly seem as if two violins are playing.
  2009, Roger T. Dean, The Oxford Handbook of Computer Music