covert vs sidelong

covert

adj
  • Secret, surreptitious, concealed. 

  • Under coverture. 

noun
  • A covering. 

  • A disguise. 

  • A feather that covers the bases of flight feathers. 

  • Area of thick undergrowth where animals hide. 

  • A hiding place. 

sidelong

adj
  • Indirect; suggestive; not straightforward. 

  • Slanting or sloping; oblique. 

  • Directed to the side; sideways. 

  • Along the side of something. 

adv
  • obliquely 

  • Towards the side; sideways. 

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