couple vs duet

couple

noun
  • That which joins or links two things together; a bond or tie; a coupler. 

  • A small number. 

  • A couple-close. 

  • Two partners in a romantic or sexual relationship. 

  • One of the pairs of plates of two metals which compose a voltaic battery, called a voltaic couple or galvanic couple. 

  • Two of the same kind connected or considered together. 

  • A turning effect created by forces that sum to zero in magnitude but produce a non-zero external torque. 

adj
  • Two or (a) small number of. 

verb
  • To cause (two animals) to copulate, to bring (two animals) together for mating. 

  • To join in sexual intercourse; to copulate. 

  • To join (two things) together, or (one thing) to (another). 

det
  • Two or a few, a small number of. 

duet

noun
  • A pair or couple, especially one that is harmonious or elegant. 

  • A musical composition in two parts, each performed by a single voice (singer, instrument or univoce ensemble). 

  • A song composed for and/or performed by a duo. 

verb
  • To perform (sing, play, etc.) as a duet. 

  • (of two people) To say at the same time, to chorus. 

  • To perform a duet. 

  • To communicate (warnings, mating calls, etc.) through song. 

How often have the words couple and duet occurred in a corpus of books? (source: Google Ngram Viewer )