# Where does the slash for abbreviations come from? **URL:** \ **Category:** Factual Questions\ **Created:** [April 27, 2009, 2:06pm UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499 "2009-04-27T14:06:11Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [April 27, 2009, 2:06pm UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499/1 "2009-04-27T14:06:11Z")
Inspired by the title of the aircraft-carrier thread (“What will US do w surplus a/c carriers?”). Now, I have never seen “aircraft” abbreviated as A/C before, but I’ve seen plenty of other similar abbreviations. The most common may be C/O for “(in) care of” used in addressing mail. Where does this style of abbreviation come from? ---
**Author:** ![Ludovic](https://avatars.discourse-cdn.com/v4/letter/l/7ab992/32.png) [@Ludovic](https://boards.straightdope.com/u/Ludovic)\ **Post date:** [April 27, 2009, 2:33pm UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499/2 "2009-04-27T14:33:42Z")
Ever since he met him, Trane knew that With Regards To was destined to share a precious moment of passion with him. But it was ever so frustrating, as if they were both part of a sitcom called Abbreviations in Grammar and the writers found it amusing to keep them forever out of each others tender arms. But this night would be different. When they got to the hotel room, drunk on the air of expanding and contracting freon(expanding and contracting, pulsating like the passion they would soon embrace,) With Regards To suddenly confessed his mutual attraction With Regards To Trane. So Trane pulled out his air conditioning unit and forcefully sucked in his dangling participle leaving him with a cool, tingly feeling all over his grammar. It felt so wrong but deep inside him, it was as if they had been destined for each other all along, no matter what cruel fate had had in store for them up until this point. ---
**Author:** ![JSexton](https://avatars.discourse-cdn.com/v4/letter/j/96bed5/32.png) [@JSexton](https://boards.straightdope.com/u/JSexton)\ **Post date:** [April 27, 2009, 4:02pm UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499/3 "2009-04-27T16:02:06Z")
_snerk_ Beautiful. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [April 27, 2009, 4:27pm UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499/4 "2009-04-27T16:27:13Z")
For what is social convention worth, when passion feels so good? Social convention is just a drag, a lumbering impediment invented by busybodies and priests. Trane looked into With Regards To’s eyes as they relaxed. It wasn’t bad. It wasn’t wrong at all. It was very very good. But underneath the afterglow, all was not quiet. The original question remained. [sub]Edit: what the _fmeep_ am I doing writing slash fiction???[/sub] ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [April 27, 2009, 4:30pm UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499/5 "2009-04-27T16:30:16Z")
I agree that a/c for aircraft carrier is uncommon. Some slashed abbreviations I’ve seen or that I use myself: b/c = because fr/ = from c/w = in connection with ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [April 27, 2009, 4:45pm UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499/6 "2009-04-27T16:45:53Z")
Interesting question. I notice that in automotive use, we talk about an A/C (air conditioning) hose and a PS (power steering) hose. ---
**Author:** ![Chez\_Guevara](https://avatars.discourse-cdn.com/v4/letter/c/aeb1de/32.png) [@Chez\_Guevara](https://boards.straightdope.com/u/Chez_Guevara)\ **Post date:** [April 28, 2009, 11:12am UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499/7 "2009-04-28T11:12:31Z")
> [@Sunspace](#): > > Inspired by the title of the aircraft-carrier thread (“What will US do w surplus a/c carriers?”). > > Now, I have never seen “aircraft” abbreviated as A/C before, but I’ve seen plenty of other similar abbreviations. The most common may be C/O for “(in) care of” used in addressing mail. > > Where does this style of abbreviation come from? Shamelessly quoting [Wikipedia](http://en.wikipedia.org/wiki/Slash_(punctuation)): > [@](#): > > UK English particularly makes use of stroke instead of hyphen in forming abbreviations. Many examples are found in writings during the Second World War. For example, ‘S/E’ means ‘single-engined’, as a quick way of writing a type of aircraft. And in the USA, “O/O” is used by trucking firms or taxi-cabs to mean “owner-operator” (or “owned and operated by”). Notice that the phrase has a hyphen, whereas the abbreviation uses the slash. This style of usage was perhaps the inspiration for what follows: > [@](#): > > The slash is often used, perhaps incorrectly, to separate the letters in a two-letter initialism such as R/C (short for radio control) or w/o (without). Purists strongly discourage this newer use of the symbol. However, since other uses of the slash with individual characters are highly context-specific, confusion is not likely to arise. Other examples include b/w (between or, sometimes, black and white), w/e (whatever, also weekend or week ending), i/o (input-output), and r/w (read-write). Note that this fails to explain why aircraft should be abbreviated to A/C, which contraction also comes as a surprise to me. I have seen b/w, or sometimes c/w, used in advertisements for 45 rpm records _e.g._ _We Can Work It Out_ b/w _Day Tripper_. In this context, b/w means ‘backed with’ and c/w ‘combined with’. Some confusion can arise with the use of w/e. When, out of sheer prurience, I used to scan the personal columns in magazines of a certain ilk, I initially thought w/e stood for weekend, as in ‘Woman seeks man, must be w/e’. Eventually, of course, I discovered that w/e was more an issue of size than a lack of availability during weekdays. On a similar theme, it wouldn’t surprise me to learn that b/w has been hijacked by sexual shorthand and now refers to a bisexual wanker. However, I haven’t read the personal ads for a while now, so I could be wrong about that. ---
**Author:** ![Wheelz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wheelz/32/5718_2.png) [@Wheelz](https://boards.straightdope.com/u/Wheelz)\ **Post date:** [April 28, 2009, 11:20am UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499/8 "2009-04-28T11:20:02Z")
I usually order my Quarter Pounder w/ cheese w/o onions. ---
**Author:** ![mnemosyne](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mnemosyne](https://boards.straightdope.com/u/mnemosyne)\ **Post date:** [April 28, 2009, 5:21pm UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499/9 "2009-04-28T17:21:27Z")
Using A/C for aircraft (not aircraft carrier… just aircraft) is pretty common in the aeronautical industry; both my husband and I have worked in that field and it’s pretty standard notation on internal documents. That doesn’t explain _why_ that abbreviation is used, but it is used a lot! ---
**Author:** ![Polycarp](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Polycarp](https://boards.straightdope.com/u/Polycarp)\ **Post date:** [April 28, 2009, 6:39pm UTC](https://boards.straightdope.com/t/where-does-the-slash-for-abbreviations-come-from/494499/10 "2009-04-28T18:39:58Z")
The following is as far as I know apocryphal. It may be true but I cannot vouch for it. 1. The percentage mark % was originally written that way to signify the fractionality of the percentage: 93% is 93/100 of unit value (100%). 93/100 got reduced to 93 /o and the slash mark picked up a o numerator to signify that it was in fact signalling a fraction. Hence 93%. 2. “(In) care of” was written c/o in imitation of the percent function. (Older or fuller typefaces include a [sup]c[/sup]/[sub]o[/sub] character [imitated here to avoid giving some browsers heart failure].) 3. With those two symbols in place, a precedent was set, and other common phrases began to be abbreviated as [first initial]/[second initial]. As noted, this is an explanation I’ve run into – but it may be purely an apocryphal folk etymology of the usage. Use with caution. Do not take more than two tablets in an eight hour period. Vpoid where prohibited by law.