indifference vs unenthusiasm

indifference

noun

  • A lack of enthusiasm. 

  • Unconcerned nonchalance. 

  • The state of being indifferent. 

  • Unbiased impartiality. 

  • Unemotional apathy. 

  • Self-identity defined through the negation of difference, non-difference. 

unenthusiasm

noun

  • Lack of enthusiasm. 

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