# Semi-What?

**URL:** <https://boards.straightdope.com/t/semi-what/3634>\
**Category:** Factual Questions\
**Created:** [March 16, 1999, 8:57pm UTC](https://boards.straightdope.com/t/semi-what/3634 "1999-03-16T20:57:00Z")\
**Posts on this page:** 17\
**Page:** 1

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**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\
**Post date:** [March 16, 1999, 8:57pm UTC](https://boards.straightdope.com/t/semi-what/3634/1 "1999-03-16T20:57:00Z")

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My lovely wife and I were driving across the country, and happened to pass a semi. You know what a semi is. I know what a semi is. But what occurred to us at 3 in the morning is that semi is actually a prefix.

So the question became semi-what? I’ve driven a truck (when I was in college), but somehow the fact that you could read was considered enough for your class A license. The finer points of linguistics just didn’t come up.

Any ideas?

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- Through the modem, past the router, over the firewall… nothing but 'Net -

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**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\
**Post date:** [March 16, 1999, 9:06pm UTC](https://boards.straightdope.com/t/semi-what/3634/2 "1999-03-16T21:06:00Z")

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Semi is short for Semi Detached. I asked a cop, he couldn’t tell me what a fully detached trailer was. That is, besides one sitting alone in a parking lot.

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Ranger Jeff  
The Idol of American Youth

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**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\
**Post date:** [March 16, 1999, 10:25pm UTC](https://boards.straightdope.com/t/semi-what/3634/3 "1999-03-16T22:25:00Z")

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> [@](#):
>
> Semi is short for Semi Detached. I asked a cop, he couldn’t tell me what a fully detached trailer was. That is, besides one sitting alone in a parking lot.

I think it is as opposed to a **fully attached** truck. Kind of like a U-Haul truck where the box is attached to the cab. I guess semi-detached sounds better than semi-attached. Kind of a glass half-empty half-full idea. 🙂

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Scoobysnax

Save water drink beer!

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**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\
**Post date:** [March 17, 1999, 3:08am UTC](https://boards.straightdope.com/t/semi-what/3634/4 "1999-03-17T03:08:00Z")

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Oh my life is complete! Every time I take a road trip I wonder this exact question, but have never actually remembered to ask. I feel like the smartest person in the world. haha. Of course, I shouldn’t, seeing as how I didn’t figure it out. But just knowing something that I’ve wondered for so long is wonderful. Oh happy day!

* * *

~_brandie_~  
“Free thinkers are dangerous.”~Serj

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**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\
**Post date:** [March 17, 1999, 4:57am UTC](https://boards.straightdope.com/t/semi-what/3634/5 "1999-03-17T04:57:00Z")

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I hate to disagree with the police, but my Driver’s Educatino book says differently. According to the book, it’s short for Semi tractor-trailer. Which I assume is half a truck (just a cab), and a trailer (what they’re hauling). Although the other definition makes sense, too.

* * *

Eagles may soar, but weasels never get sucked into jet engines…

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**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\
**Post date:** [March 17, 1999, 5:07am UTC](https://boards.straightdope.com/t/semi-what/3634/6 "1999-03-17T05:07:00Z")

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\>\>Semi is short for Semi Detached.\>\>Ranger Jeff

Why does this conflict with MW online (not to mention your mailbag answer)?

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**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\
**Post date:** [March 17, 1999, 5:35am UTC](https://boards.straightdope.com/t/semi-what/3634/7 "1999-03-17T05:35:00Z")

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A semi tralier is indeed different from a “regular” trailer. A semi trailer only has wheels at the back end, and rests its front on the tractor. A “regular” trailer (or a full trailer, I guess) has wheels at the front and the back, and only has a tounge that attaches to a tractor. Think of a farm trailer, the kind that carries hay around here…wheels at all corners.

## Must a semi trailer be, philosophically, ipso facto semi not be?

Jeremy…

I can think of no more stirring symbol of man’s humanity to man than a fire engine - Kurt Vonnegut

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**Author:** ![system](https://global.discourse-cdn.com/straightdope/original/2X/e/e489c3b7d8fce19c4b355dd4fc3f88cc39c34b87.png) [@system](https://boards.straightdope.com/u/system)\
**Post date:** [March 17, 1999, 6:55am UTC](https://boards.straightdope.com/t/semi-what/3634/8 "1999-03-17T06:55:00Z")

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A semi tralier is indeed different from a “regular” trailer. A semi trailer only has wheels  
at the back end, and rests its front on the tractor. A “regular” trailer (or a full trailer, I  
guess) has wheels at the front and the back, and only has a tounge that attaches to  
a tractor.

On the other hand, the things you tow a forklift or whatever on only have a single set of wheels and a tongue and they’re just called trailers. Go figure. I’m referring to the trailers we use at work (landscaping company) to haul things around on. I certainly wouldn’t call it a semi-trailer.

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**Author:** ![sly](https://avatars.discourse-cdn.com/v4/letter/s/e56c9b/32.png) [@sly](https://boards.straightdope.com/u/sly)\
**Post date:** [October 1, 1999, 1:09am UTC](https://boards.straightdope.com/t/semi-what/3634/9 "1999-10-01T01:09:00Z")

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Ahhhh, the good old days.

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**Author:** ![mangeorge](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@mangeorge](https://boards.straightdope.com/u/mangeorge)\
**Post date:** [October 1, 1999, 2:50am UTC](https://boards.straightdope.com/t/semi-what/3634/10 "1999-10-01T02:50:00Z")

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## Main Entry: semi·trail·er Pronunciation: 'se-"mI-"trA-l&r, 'se-mE-, -mi- Function: noun Date: 1919 1 : a freight trailer that when attached is supported at its forward end by the fifth wheel device of the truck tractor 2 : a trucking rig made up of a tractor and a semitrailer

Whaddaya know, youse guys si right!  
Peace,  
mangeorge

* * *

Work like you don’t need the money…  
Love like you’ve never been hurt…  
Dance like nobody’s watching! …(Paraphrased)

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**Author:** ![NanoByte](https://avatars.discourse-cdn.com/v4/letter/n/ecc23a/32.png) [@NanoByte](https://boards.straightdope.com/u/NanoByte)\
**Post date:** [October 1, 1999, 6:09am UTC](https://boards.straightdope.com/t/semi-what/3634/11 "1999-10-01T06:09:00Z")

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Well, when I was a pup, the public, at least, actually mostly only called – pretty much the whole rig – a ‘semi-trailer’. Only later did the public start calling them ‘semis’, ‘tractor-trailers’, ‘rigs’, ‘18-wheelers’, etc.

Ray (Keep on trailin’.)

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**Author:** ![C\_K\_Dexter\_Haven](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@C\_K\_Dexter\_Haven](https://boards.straightdope.com/u/C_K_Dexter_Haven)\
**Post date:** [October 1, 1999, 4:31pm UTC](https://boards.straightdope.com/t/semi-what/3634/12 "1999-10-01T16:31:00Z")

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You should all believe Jeff, he always speaks true.

Also, you should check the Archives (altho, I have to say, the search engine didn’t turn this up when I searched for “semi” for “trailer” nor for “truck”, so I’m really not being critical with ya for not finding it in the Archives.)

Link: [http://www.straightdope.com/mailbag/msemi.html](http://www.straightdope.com/mailbag/msemi.html)

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**Author:** ![kellibelli](https://avatars.discourse-cdn.com/v4/letter/k/e480ec/32.png) [@kellibelli](https://boards.straightdope.com/u/kellibelli)\
**Post date:** [October 2, 1999, 5:58am UTC](https://boards.straightdope.com/t/semi-what/3634/13 "1999-10-02T05:58:00Z")

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You are all wrong!  
Semi refers to the _driver!_

Semi-educated  
semi-intelligent  
semi-qualified  
etc.  
At least that’s what it means in canada…

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**Author:** ![mr\_trucker](https://avatars.discourse-cdn.com/v4/letter/m/8edcca/32.png) [@mr\_trucker](https://boards.straightdope.com/u/mr_trucker)\
**Post date:** [October 2, 1999, 2:00am UTC](https://boards.straightdope.com/t/semi-what/3634/14 "1999-10-02T02:00:00Z")

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That is one of the dumbest things I have read on this board.  
I’m not trying to start a flame war here, but that really irks me.  
Most of the drivers I know are very well qualified, none of them are ‘semi-intelligent’ as you put it, and I know several drivers that have college degrees.  
What I would like to know is where do people get information like that. The drivers that I know and work with daily do everything they can to be professional at all times and do nothing to give those impressions at all.

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**Author:** ![Omniscient](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omniscient/32/3290_2.png) [@Omniscient](https://boards.straightdope.com/u/Omniscient)\
**Post date:** [October 2, 1999, 3:03am UTC](https://boards.straightdope.com/t/semi-what/3634/15 "1999-10-02T03:03:00Z")

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Jokes, god damn it, just jokes. Take a valium.

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**Author:** ![kellibelli](https://avatars.discourse-cdn.com/v4/letter/k/e480ec/32.png) [@kellibelli](https://boards.straightdope.com/u/kellibelli)\
**Post date:** [October 2, 1999, 3:01pm UTC](https://boards.straightdope.com/t/semi-what/3634/16 "1999-10-02T15:01:00Z")

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well, that proves the semi-intelligent assertion. 😉  
Its just a joke for pete’s sake!

My own _father_ was a trucker for years, my Dad, and my brother are still involved in the industry, my ex, (shitboy) drives truck, as does his father and uncle…(trust me, the above description fits shitboy pretty well)  
My making a generalization like that is no different than Coldfire’s thread about women drivers…do I think all truckers are morons…of course not!

But some are.

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**Author:** ![Temujin](https://avatars.discourse-cdn.com/v4/letter/t/e0b2c6/32.png) [@Temujin](https://boards.straightdope.com/u/Temujin)\
**Post date:** [October 3, 1999, 5:27am UTC](https://boards.straightdope.com/t/semi-what/3634/17 "1999-10-03T05:27:00Z")

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> [@](#):
>
> Most of the drivers I know are very well qualified, none of them are ‘semi-intelligent’ as you put it, and I know several drivers that have college degrees.  
> What I would like to know is where do people get information like that.

I don’t doubt that what you say is true. On the other hand, the most dangerous and potentially life-threatening situatons I’ve been in on the road almost all involved semi truck drivers. On separate occasions, two friends of mine were run off the road by semi truck drivers.

I’m sure all of us have had the experience of a semi truck driver tailgating us on the highway. It’s incredibly dangerous. I witnessed an accident in which a semi truck driver rear-ended a slower-moving car in the right lane of an interstate highway, even though there was plenty of room to pass. The car literally became airborn. It’s amazing nobody was killed.

I’m willing to accept that most truck drivers behave responsibly, but there will always be some who do not. When I almost get squashed into the pavement or smeared against an embankment, it’s definitely the bad truck drivers that make the lasting impression.
