tramline

The rails that a tram runs on.

Either of the two pairs of sidelines marked on a tennis court which mark the outside of the singles and doubles playing areas.

A scratch on a film, usually vertical, that extends through multiple frames.

The tramline is therefore much less obvious on the screen. Also, if the scratch is on the base (i.e., on the back of the film), then it will not be in sharp focus.

A mark or bruise having the shape of two parallel lines.

a tramline scar

The well-reported "tramlines" or parallel punctate scars on either side of the vein were seen in only four patients.

A pair of vertical bars (||) placed to the left of the headword in certain editions of the OED to indicate that the term is "alien or not fully naturalized" (such as a recent borrowing).

Those words that [James] Murray classified as denizens and aliens, as well as those casuals approaching these two prior categories, were marked by two parallel lines beside the headword (||), a symbol known by the in-house term tramline. Murray himself admitted to the inherent subjectivity of his method of classification, which unsurprisingly led to a number of inconsistencies in the use of tramlines, and may even have contributed to the patchiness of the OED's regional coverage that Weiner acknowledged many years later.

Of a vehicle: to tend to follow the contours of the ground with its wheels.