1. 
   Mainline
   [flight] A mainline flight is a flight operated by an airline`s main operating unit, rather than by regional alliances, regional code-shares or regional subsidiaries. In the USA, examples of mainline passenger airline flights include those operated by American Airlines, Delta Air Lines, and ...
   Found op http://en.wikipedia.org/wiki/Mainline_(flight)
   
   
2. 
   mainline
   [v] - inject into the vein
   Found op http://www.webdictionary.co.uk/definition.php?query=mainline
   
   
3. 
   mainline
   1) In an established group 2) Inject 3) Inject into the vein 4) Suburban philadelphia area
   Found op http://www.mijnwoordenboek.nl/EN/crossword-dictionary/mainline/1
   
   

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