edder vs viper

edder

noun
  • An adder or snake. 

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

viper

noun
  • Any venomous snake. 

  • A dangerous, treacherous, or malignant person. 

  • A person who smokes marijuana. 

  • A venomous snake in the family Viperidae. 

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