dawn vs onset

dawn

noun
  • The earliest phase of something. 

  • The rising of the sun. 

  • The morning twilight period immediately before sunrise. 

  • The time when the sun rises. 

verb
  • To begin to give promise; to begin to appear or to expand. 

  • To begin to brighten with daylight. 

  • To start to appear or be realized. 

onset

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

  • 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. 

  • A setting about; a beginning. 

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