optimum vs worst

optimum

noun
  • The best or most favorable condition, or the greatest amount or degree possible under specific sets of comparable circumstances. 

adj
  • The best or most advantageous; surpassing all others. 

worst

noun
  • Something or someone that is the worst. 

adj
  • Most unfavorable. 

  • Used with the definite article and an implied noun: something that is worst. 

  • Most inferior; doing the least good. 

  • Most harmful or severe. 

verb
  • To outdo or defeat, especially in battle. 

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