thoo vs whom

thoo

pron
  • Thou; singular informal form of you. 

whom

pron
  • As the object of a verb. 

  • The person(s) whom; whomever. 

  • As the object of a preposition. 

  • Used to refer to a previously mentioned person or people. 

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