in earnest vs rigorously

in earnest

adv

  • With considerable commitment, determination, or effect; significantly. 

  • Having a sincere intent. 

adj

  • Sincere; determined; truthful. 

rigorously

adv

  • In a rigorous manner. 

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