cobra vs edder

cobra

noun
  • A type of lanyard knot, thought to resemble a snake in its shape. 

  • Any of various venomous snakes of the family Elapidae. 

edder

noun
  • An adder or snake. 

  • Flexible wood worked into the top of hedge stakes, to bind them together. 

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