(aviation) An airline's main operating unit, as opposed to codeshares or regional subsidiaries. / (rail transport) The principal route or line of a railway.

Normal, principal or standard. / (rail transport) Of or pertaining to the principal route or line of a railway.

(slang) To inject (a drug) directly into a vein. / (by extension, informal, transitive) To consume voraciously.

Third-person singular simple present indicative form of mainline

simple past tense and past participle of mainline

A member of the mainstream. / Someone who mainlines (injects drugs directly into their veins).

plural of mainliner

present participle of mainline