most vs mostest

most

noun
  • A record-setting amount. 

  • The greatest amount. 

  • The greater part. 

pron
  • The greater part of a group, especially a group of people. 

adv
  • To a great extent or degree; highly; very. 

  • Almost. 

  • Forms the superlative of many adjectives. 

mostest

adj
  • most. 

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