encroachment vs onset

encroachment

noun
  • An entry into a place or area that was previously uncommon; an advance beyond former borders; intrusion; incursion. 

  • That which is gained by such unlawful intrusion. 

  • An intrusion upon another's possessions or rights; infringement. 

  • An unlawful diminution of the possessions of another. 

onset

noun
  • A setting about; a beginning. 

  • The initial portion of a syllable, preceding the syllable nucleus. 

  • The beginning of a musical note or other sound, in which the amplitude rises from zero to an initial peak. 

  • The initial phase of a disease or condition, in which symptoms first become apparent. 

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