chief vs mainline

chief

adj
  • Primary; principal. 

  • Intimate, friendly. 

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. 

verb
  • To smoke cannabis. 

mainline

adj
  • Normal, principal or standard. 

  • Of or pertaining to the principal route or line of a railway. 

  • Of or pertaining to a surface railway as distinct from an underground, elevated or light rail one. 

  • Of a sequence of opening moves: being part of a main line ("a standard sequence of opening moves considered to be best play"). 

noun
  • In longline fishing the central line to which the branch lines with baits are attached. 

  • An airline's main operating unit, as opposed to codeshares or regional subsidiaries. 

  • The principal route or line of a railway. 

  • A principal vein into which a drug can be injected. 

  • The main repository for a software project, from which different versions (forks) may be split off. 

  • The pipeline carrying wastewater to the public drains or a septic tank. 

verb
  • To integrate (code, etc.) into the main repository for a software project, rather than separate forks. 

  • To inject (a drug) directly into a vein. 

  • To consume voraciously. 

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