viperish vs virulent

viperish

adj
  • spiteful; treacherous 

  • In the manner of a viper. 

virulent

adj
  • Extremely hostile or malicious; intensely acrimonious. 

  • Of a pathogen: replicating within its host cell, then immediately causing it to undergo lysis. 

  • Of a disease or disease-causing agent: malignant, able to cause damage to the host. 

  • Of animals, plants, or substances: extremely venomous or poisonous. 

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