skulking vs sly

skulking

noun
  • The action of one who skulks. 

sly

adv
  • Slyly. 

adj
  • Done with, and marked by, artful and dexterous secrecy; subtle 

  • Light or delicate; slight; thin. 

  • Artfully cunning; secretly mischievous; wily. 

  • Dexterous in performing an action, so as to escape notice 

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