glimpse vs look out

glimpse

verb
  • To see or view briefly or incompletely. 

  • To appear by glimpses. 

noun
  • A brief look, glance, or peek. 

  • A sudden flash. 

  • A faint idea; an inkling. 

look out

verb
  • Used other than figuratively or idiomatically: see look, out. 

  • To be vigilant and aware often as an imperative to alert a person to danger. 

  • To find by looking: to hunt out. 

  • To be facing (used with "on"). 

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