keep out vs lock out

keep out

verb
  • To restrain someone or something from entering a place or condition. 

  • To refrain from entering a place or condition. 

lock out

verb
  • To inadvertently prevent (a person, particularly oneself) from entering a place, by leaving it locked. 

  • To prevent from accessing a data structure. 

noun
  • An event in which an employer bars employees from working as a tactic in negotiating terms of employment, particularly in response to a strike or threat to strike. 

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