ish vs pro rata

ish

adv
  • somewhat, reasonably, fairly 

  • about, approximately 

noun
  • The letter which stands for the sh sound /ʃ/ in Pitman shorthand. 

  • Shit. 

pro rata

adv
  • In proportion to some factor that can be exactly calculated. 

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