cloak vs keep out of sight

cloak

verb
  • To cover up, hide or conceal. 

  • To render or become invisible via futuristic technology. 

  • To cover as with a cloak. 

noun
  • A long outer garment worn over the shoulders covering the back; a cape, often with a hood. 

  • That which conceals; a disguise or pretext. 

  • A blanket-like covering, often metaphorical. 

  • A text replacement for an IRC user's hostname or IP address, making the user less identifiable. 

keep out of sight

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