overswell vs spillover

overswell

noun
  • An excessive or sudden increase or flood (of something). 

verb
  • To cause (something) to be too swollen or large; to become too swollen or large. 

  • To swell or rise above (something, especially the rim of a container, the sides of something hollow, etc.). 

spillover

noun
  • That which overflows; the excess or side effect. 

  • The spread of infectious disease between different species of animal and particularly to humans. 

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