in the background vs low-key

in the background

low-key

adv
  • Kind of. 

  • In a low-key or surreptitious manner; secretively; on the down-low. 

adj
  • Dark; characterised by dark tones and muted colours. 

  • Restrained, subtle, not trying to attract attention. 

How often have the words in the background and low-key occurred in a corpus of books? (source: Google Ngram Viewer )