main vs mainline

main

adj
  • Of chief or leading importance; prime, principal. 

  • Big; angry. 

  • Chief, most important, or principal in extent, size, or strength; consisting of the largest part. 

  • Belonging to or connected with the principal mast in a vessel. 

noun
  • That which is chief or principal; the chief or main portion; the bulk, the greater part, gross. 

  • The primary character that one plays in a video game in which one can play more than one character. 

  • The high seas. 

  • A large cable or pipe providing utility service to an area or a building, such as a water main or electric main. 

  • A banker's shovel for coins. 

adv
  • Exceedingly, extremely, greatly, mightily, very, very much. 

verb
  • To mainly play a specific character or side, or with specific equipment, during a game. 

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"). 

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. 

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. 

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