split up vs undo

split up

verb
  • separate, disassociate, cause to come apart. 

  • Cease to be together, break apart from the group. 

adj
  • Divided or separated. 

undo

verb
  • To impoverish or ruin, as in reputation; to cause the downfall of. 

  • To reverse the effects of an action. 

  • To unfasten. 

noun
  • An operation that reverses a previous action. 

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