inroad vs onset

inroad

noun
  • Often followed by in, into, or on: initial progress made toward accomplishing a goal or solving a problem. 

  • An advance into enemy territory, an attempted invasion; an encroachment, an incursion. 

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 inroad and onset occurred in a corpus of books? (source: Google Ngram Viewer )