know vs look up

know

verb
  • To have knowledge; to have information, be informed. 

  • To perceive the truth or factuality of; to be certain of or that. 

  • To experience. 

  • To understand or have a grasp of through experience or study. 

  • To be or become aware or cognizant. 

  • To be able to play or perform (a song or other piece of music). 

  • To be acquainted or familiar with; to have encountered. 

  • To be aware of; to be cognizant of. 

  • To recognize as the same (as someone or something previously encountered) after an absence or change. 

noun
  • Knowledge; the state of knowing. 

  • Knowledge; the state of knowing; now confined to the fixed phrase ‘in the know’ 

look up

verb
  • To obtain, or seek to obtain, information about something. 

  • To reconnect or meet with someone that one used to know. 

  • To obtain information about something from a reference book. 

  • To have better prospects. 

  • To enter a query into a database or search engine. 

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

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