thenceforth vs whilom

thenceforth

adv

  • From that time on. 

whilom

adv

  • At some time in the past; formerly, once upon a time. 

adj

  • At some time in the past; former, sometime. 

conj

  • During the same time that; while. 

  • Up to the time that; till, until. 

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