linkage vs union

linkage

noun
  • A mechanical device that connects things. 

  • A connection or relation between things or ideas. 

  • The act or result of linking: the combination of multiple object files into one executable, library, or object file. 

  • A United States foreign policy, during the 1970s détente in the Cold War, of persuading the Soviet Union to co-operate in restraining revolutions in the Third World in return for nuclear and economic concessions. 

  • The property of genes of being inherited together. 

  • A set of definitely related languages for which no proto-language can be derived, typically a group of languages within a family that have formed a sprachbund. 

union

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

  • 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. 

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

  • 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. 

  • 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 linkage and union occurred in a corpus of books? (source: Google Ngram Viewer )