LEO:
semi (Brit.) [coll.] - die Doppelhaushälfte
semi - halb-
semi-trailer [abbr.: STLR] [autom.] - der Auflieger (Sattelanhänger)
semi-trailer - der Sattelanhänger (Eisenbahn)
semi-trailer - der Sattelauflieger (Eisenbahn)
road semi-trailer - der Sattelanhänger (Eisenbahn)
road semi-trailer [tech.] - der Sattelanhänger
road semi-trailer - der Sattelauflieger (Eisenbahn)
road semi-trailer [tech.] - der Sattelauflieger
eighteen-wheeler (also: 18-wheeler) [Amer.] [coll.] - der Sattelschlepper [i-link broken]
tractor-trailer [autom.] - der Lastzug, das Sattelkraftfahrzeug, der Sattelschlepper, der Sattelzug
tractor-trailer rig [autom.] - der Sattelzug

Siehe auch: chains required for all semis
Siehe auch: to drive a semi on a nickels's worth of gas
Siehe auch: semi-trailer coupling - die Aufliegerkupplung
Siehe auch: Sattelauflieger u. Lastwagen - semi truck and...
(there may be many others, but the forum search will only go back as far as March 2007 because there is no way to specify exactly 'semi' and no more, so you can't avoid pulling up things like Seminararbeit and semi-liquid and so on -- another item on my long-term wish list)

Wikipedia:
A semi-trailer truck or tractor-trailer (colloquially known as a transfer truck, 18-wheeler, semi, Diesel, Mack truck [although this is actually just one brand of truck maker], or big rig in the U.S., and transport in Canada; as a semi in Australia or New Zealand; and as an articulated lorry (artic) in the UK and Ireland) is an articulated truck or lorry consisting of a towing engine (tractor in the U.S., prime mover in Australia, and truck in the UK, Canada and New Zealand), and a semi-trailer (plus possible additional trailers) that carries the freight. In the UK, the term juggernaut is sometimes used for articulated lorries.
http://en.wikipedia.org/wiki/Semi-trailer_truck


web examples:
• Even worse is heading between Saskatoon and Yorkton at 120, and being passed by a semi going 130. Absolutely terrifying.
• I was driving in a near white out in Utah, when I was passed by a semi going at least 70 MPH. I know he was a local driver
• It feels rock-solid on the highway, even when you're being passed by a semi.
• I'd sure hate to be paying for the fuel in both those tanks on one of those big semis.
• The 2002 models have daytime running lamps which offer good safety on the roads, especially on the interstates next to those big semis.
• The solar car had just descended a hill and was traveling at 45-50 mph when a huge semi came speeding by and passed the car.
• A huge semi-trailer truck like this one is crossing Wisconsin and Minnesota over the next two days
• A young man has quite the story to tell after his wheelchair got lodged in the grille of a semi truck, which pushed the chair and the man
• I was in a horrible motorcycle accident where I was run over by a semi truck (yes, you read it right…run over)
• The State Patrol says two vehicles, including a semi truck, slammed into a Buick LeSabre heading in the wrong direction on westbound 494
• A Darien man ran a red light on Route 47 before his semi-trailer slammed into a sedan and killed two people last month
• The semi-trailer slammed into the three-carriage Melbourne-bound passenger train at the crossing about six kilometres north of Kerang
• The accident happened just before 5pm when a 15-tonne HGV Business Post lorry with a semi-trailer skidded on some oil and overturned
• It looked like a semi-trailer skidded and crashed into the median

Since 'semi' is synonymous with 'eighteen-wheeler,' which is already in LEO, I trust it's not necessary to repeat all the basic definitions. Or if it is, maybe someone else could help, since I'm not where all my dictionaries are.

I don't understand the exact difference, if any, between a -schlepper, -anhänger, and -auflieger -- are these only the towing part and the towed part, respectively, or can any or all of them also mean the whole truck rig?

Nor do I know what any of this could possibly have to do with railroads.

So it might help to review all the existing entries, since to me at least, they don't seem very consistent, and some of them do seem to be duplicated, and others missing.

But my basic point is that all the following terms are used interchangeably in AE for a big, long truck (one heavy cab pulling one large enclosed trailer):

tractor-trailer
tractor-trailer truck
semi-trailer
semi-trailer truck
semi [ugs.]
semi truck [ugs.] (IMO should not be hyphenated, as it is not a half truck)
eighteen-wheeler [ugs.]


So something needs to be added to LEO so that Doppelhaushälfte [Brit.] isn't the only choice.

I've marked these [Amer.] above, since the LEO dropdown menus allow only one choice, but according to Wikipedia they're also [Aus] & [NZ]; maybe someone with Macquarie (sp?) or something could confirm.





OT: Whoa. I think this is a big bug in the new layout; when I hit 'neu' above to add a related suggestion, all the text entry fields disappear from the screen, leaving only blank space. I had to use the back arrow and then the forward arrow to get them back, but then the new fields I wanted were gone. So I'm condensing above to just one additional suggestion.