heed vs onlook

heed

verb
  • To mind; to regard with care; to take notice of; to attend to; to observe. 

noun
  • Careful attention. 

onlook

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

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

  • One's perspective or outlook. 

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

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