Mainline (pronounced meyn-lahyn)
(1) A slang term for the intravenous (injected directly into a vein as opposed to subcutaneous (skin popping)) use of injectable drugs (historically associated most with opium and its derivatives, especially heroin); a principal or prominent vein into which a drug can be injected.
(2) To use, enjoy or imbibe something without restriction.
(3) The normal, established, or widely accepted position; major (a synonym of mainstream although without any of the the negative connotations mainstream has in recent years acquired.
(4) In rail transport (1) of or pertaining to the principal route or line of a railway or (2) of or pertaining to a surface railway as distinct from an underground, elevated or light rail one (originally as main line or main-line).
(5) In computing, to integrate (code etc) into the main repository for a software project, rather than separate forks.
(6) In civil aviation, an airline's main operating unit, as opposed to codeshares or regional subsidiaries (by extension from the railroad use).
(7) As Mainlinie (line of the Maine), a (historical and political) boundary between northern and southern Germany, roughly following the River Main.
(8) In chess, of a sequence of opening moves, the principal, most important, or most often played variation of such (ie the "main line", the orthodox sequence of opening moves considered to be "best play").
(9) In foodie slang, voraciously to consume.
(10) In longline fishing, the central line to which the branch lines with baits are attached.
(11) In plumbing, the pipeline carrying wastewater to the public drains or a septic tank.
(12) In the US and Australia, related but different models of Ford cars sold during the 1950s.
1841 (1933-1934 as applied to injectable drugs): All senses of mainline (sometimes variously as main-line or with initial capital) are Americanisms and a compound of main + line. Main is from the Middle English mayn, main, maine, mæin & meyn, from main (noun) and related to the Old English mægen (strong, main, principal) and the Old Norse megn & megenn (strong, main). It was cognate with Old High German megīn (strong, mighty) from which Modern German gained Möge & Vermögen (power, wealth) and akin to the Old English magan (to be able to). Line is from the Middle English line & lyne, from Old English līne (line, cable, rope, hawser, series, row, rule, direction) from the Proto-Germanic līnǭ (line, rope, flaxen cord, thread) from the Proto-Germanic līną (flax, linen), from the primitive Indo-European līno (flax). Influenced in Middle English by the Middle French ligne (line), from Latin linea, it was cognate with the Scots line (line), the North Frisian liin (line), the West Frisian line (line), the Dutch lijn (rope, cord), the German Leine (line, rope), the Danish line (rope, cord), the Swedish lina (line, rope, wire) and the Icelandic lína (line). It was related also to Dutch lijn (flax), the German Lein (flax, linen), the Gothic lein (linen, cloth), the Latin linea (linen, thread, string, line) & linum (flax, thread, linen, cable), the Ancient Greek λίνον (línon) (flax, linen, thread, garment), the Old Church Slavonic линъ (linŭ) (flax), the Russian лён (ljon) (flax), the Lithuanian linai (flax) and the Irish līn (lion) (flax). The oldest sense of the word is "rope, cord, thread"; from this the senses "path" & "continuous mark" were derived. Mainline is a noun in the sense of railways and a verb (used without object) if injecting drugs; those doing the latter known, inter alia, as "mainers" or "mainliners", the mainlined not infrequently ending up on a pathologist's autopsy table. Mainline is a noun, verb & adjective, mainliner is a noun and mainlinging & mainlined are verbs; the noun plural is mainlines.
1952 Ford Mainline Business Coupe (US).
Ford in the US produced the Mainline between 1952-1956. It was the base-model of its three tier offering (Ford at that time manufacturing in the US offering just a single range of passenger cars), the more highly specified models being the Customline and Crestline. The name was dropped for 1957 when the Custom nameplate was introduced although this had nothing to do with the association of “mainline” with injecting drug users. Although that connection had existed since 1933, it would be until well into the 1960s it came into common use in this sense. In the US, the Mainline was offered as two & four door sedans and station wagons (the latter which in England was sometimes called a shooting brake) and two door coupé (the convertibles were restricted to the more expensive lines).
1956 Ford Mainline "Coupé Utility" (Australia).
However, Australia was a smaller market and neither the three trim options nor all the body styles were offered, sales between 1952-1959 restricted to the four-door Customline, a limited number of station wagons and a locally developed “coupé utility”, a kind of light pickup which had been a feature of the Australian market since the 1930s. The coupé utility used the Mainline name and was built on the station wagon chassis with the addition of the convertible’s X-member to permit the higher load carrying capacity, a further quirk being the Australian Fords continued until 1954 to use the old flathead V8 which had ceased to be used in the US in 1953, local models not adopting the new overhead valve (OHV) Y-Block V8 until 1955. The Mainline remained in the Australian lineup until 1959 when the new Fairlane replaced the big car but Ford didn’t develop a coupé utility version, this body style offered on the compact platform the next year when the Falcon (1960-2016) entered local production.
Map of southern England's Great Western Main Line.
Main Line had since 1841 been used generally to mean "principal line of a railway" and the Main Line was once Philadelphia's most desired suburban district. Once just another rural hamlet, in the 1870s & 1880s it was transformed by the Pennsylvania Railroad Company which built expensive housing developments and hotels, hence the association of "Main Line" with the meaning "affluent area of residence", noted by 1917 and eventually used in that sense without capital letters and as the single-word mainline. Essentially creating a fashionable suburb, the Railroad's urban development project linked Philadelphia to Paoli along the Paoli Local train-line via the station stops Overbrook, Merion, Narberth, Wynnewood, Ardmore, Haverford & Bryn Mawr. Eventually, the Main Line connected Philadelphia with Pittsburgh via Harrisburg but was later split into two lines, Amtrak's Philadelphia to Harrisburg Main Line and the Norfolk Southern Railway's Pittsburgh Line.
An emulation of Lindsay Lohan's vascular system; the thicker veins and arteries being the "main lines" (left) and Philadelphia's rail network, again (following the same practice), the thickest lines indicate Main Line status (right).
The original slang among drug users, dating from 1933 used mainline as a noun, referring the principal or prominent vein into which a drug was most effective injected. The verb in the sense of "inject (drugs) intravenously" was noted the following year although the associated verb mainlining didn't enter regular use until the mid-1960s and the unfortunate companion verb mainlined (dead from a drug overdose) soon followed, used in that sense by Mimi Fariña (1945–2001) for the Joan Baez (b 1941) song In the Quiet Morning (1970) which noted the death of Janis Joplin (1943–1970). Joplin's death, although technically caused by an impact injury, happened under the influence of heroin. Counterintuitively, despite injecting drug-use being so obviously associated with veins and arteries, it seems it was the imagery of main and secondary railway lines rather than the human vascular system (also called the circulatory system) that prompted the simile of mainline in drug-related slang. It was probably because of the general familiarity with the word being used to describe train tracks and the often-seen graphical representation of them at stations and in carriages. Even in medicine, mainline appears hardly used by physicians when speaking of arteries and veins, the term apparently not useful within the profession because of the need for precision when discussing such things although it may be handy for pathologists who tend often to work in retrospect. However, there are citations where physicians and neurologists have adopted a similar metaphor (based perhaps on the rabbit warrens that are hospitals) to explain the process of the brain using the “back passages” to restore blood-flow to areas affected by a stroke which has blocked the “main passage”, again drawing on the idea of primary and secondary lines.
In the Quiet Morning by Mimi Farina © Universal Music Publishing Group, recorded by Joan Baez (1970).