main line
verb(main-line)
to take by or as if by injecting into a principal vein
main line
verb(main-line)
to mainline a narcotic drug
main line
adjective(main-line)
being part of an established group; also : being in the mainstream
main line
noun(main-line)
a principal highway or railroad line
main line
noun(main-line)
a principal vein of the circulatory system