constraint vs vampirism

constraint

noun
  • An irresistible force or compulsion. 

  • A condition that a solution to an optimization problem must satisfy. 

  • A linkage or other restriction that maintains database integrity. 

  • The repression of one's feelings. 

  • Something that constrains; a restriction. 

vampirism

noun
  • extortion 

  • practices associated with vampires, in particular blood-drinking and the draining of a victim's life-force. 

  • Systemic lupus erythematosus (autoimmune disease) 

  • the state of being a vampire 

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