ophidian vs viper

ophidian

noun
  • Any species of the suborder Serpentes; a snake or serpent. 

adj
  • Of or pertaining to the suborder Serpentes; of, related to, or characteristic of a snake or serpent. 

viper

noun
  • A venomous snake in the family Viperidae. 

  • A dangerous, treacherous, or malignant person. 

  • A person who smokes marijuana. 

  • Any venomous snake. 

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