mainliner

plural mainliners

1. A member of the mainstream.

   Mainliners view sociology as a profession or occupation, and marginals are antisociologists and unsociologists.

   2017, Shulamit Reinharz, On Becoming a Social Scientist

   1 more example

   […] discusses those who belong to the discipline's dominant cults, the mainliners, and their relations with the marginals and mavericks.

   1990, Elizabeth B. Lee, Sociology For People: A Caring Profession, page 110

2. Someone who mainlines (injects drugs directly into their veins).
3. A prisoner held within the general population of a prison.