crux vs helter-skelter

crux

noun
  • A puzzle or difficulty. 

  • The basic, central, or essential point or feature. 

  • The critical or transitional moment or issue, a turning point. 

  • The hardest point of a climb. 

  • A cross on a coat of arms. 

helter-skelter

noun
  • Confusion or turmoil. 

  • A helical fairground slide. 

adv
  • In confused, disorderly haste. 

adj
  • Carelessly hurried and confused. 

How often have the words crux and helter-skelter occurred in a corpus of books? (source: Google Ngram Viewer )