chief vs necessary

chief

verb
  • To smoke cannabis. 

noun
  • A leader or head of a group of people, organisation, etc. 

  • An informal term of address. 

  • The principal part or top of anything. 

  • An informal term of address for a Native American or First Nations man. 

  • The top part of a shield or escutcheon; more specifically, an ordinary consisting of the upper part of the field cut off by a horizontal line, generally occupying the top third. 

adj
  • Primary; principal. 

  • Intimate, friendly. 

necessary

adj
  • Unavoidable, inevitable. 

  • Required, essential, whether logically inescapable or needed in order to achieve a desired result or avoid some penalty. 

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