dichotomy vs disunion

dichotomy

noun
  • A separation or division into two; a distinction that results in such a division. 

  • The division of a genus into two species; a division into two subordinate parts. 

  • A phase of the moon when it appears half lit and half dark, as at the quadratures. 

  • Such a division involving apparently incompatible or opposite principles; a duality. 

  • The division of a class into two disjoint subclasses that are together comprehensive, as the division of man into white and not white. 

  • Division and subdivision; bifurcation, as of a stem of a plant or a vein of the body into two parts as it proceeds from its origin; often successive. 

disunion

noun
  • separation of a union 

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