least vs worst

least

noun
  • Something of the smallest possible extent; an indivisible unit. 

det
  • The most little; the smallest amount or quantity of something. 

adv
  • Used for forming superlatives of adjectives, especially those that do not form the superlative by adding -est. 

  • In the smallest or lowest degree; in a degree below all others. 

prep
  • At least. 

  • What a stupid white privileged POS I am! Least I call myself out. 

  • 2019 December, Justin Blackburn, The Bisexual Christian Suburban Failure Enlightening Bipolar Blues, page 79 

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 least and worst occurred in a corpus of books? (source: Google Ngram Viewer )