duet vs union

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. 

union

noun
  • The act of uniting or joining two or more things into one. 

  • An affiliation of several parishes for joint support and management of their poor; also the jointly-owned workhouse. 

  • That which is united, or made one; something formed by a combination or coalition of parts or members; a confederation; a consolidated body; a league. 

  • A data structure that can store any of various types of item, but only one at a time. 

  • A trade union; a workers' union. 

  • An association of students at a university for social and/or political purposes; also in some cases a debating body. 

  • A joint or other connection uniting parts of machinery, such as pipes. 

  • The act or state of marriage. 

  • The set containing all of the elements of two or more sets. 

  • The state of being united or joined; a state of unity or harmony. 

adj
  • Belonging to, represented by, or otherwise pertaining to a labour union. 

verb
  • To combine sets using the union operation. 

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