glimpse vs onlook

glimpse

noun
  • A brief look, glance, or peek. 

  • A sudden flash. 

  • A faint idea; an inkling. 

verb
  • To see or view briefly or incompletely. 

  • To appear by glimpses. 

onlook

noun
  • The act of looking on (something); observation. 

  • One's perspective or outlook. 

  • That which is looked at, regarded, or considered. 

verb
  • To look on or look at; watch; observe; view; regard. 

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