kryptonite vs milksop

kryptonite

noun
  • The one weakness of something or someone that is otherwise invulnerable, an Achilles heel. 

milksop

noun
  • An easily frightened, ineffectual, or weak person. 

  • A piece of bread sopped in milk. 

  • A dish consisting of bread pieces in a bowl, sprinkled with sugar and covered in hot milk. 

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