I remember when staying a few months in the US years ago that I saw some people using the abbreviations below. However, I can't exactly remember in which contexts I encountered them, (whether I saw my teachers using them when writing something on the board, in papers or in personal notes etc.)

So my question is: Are those abbreviations below commonly used and in which contexts is it okay to use them (e.g. formal texts, personal notes,... or better only used in personal note taking?)

  • w/o without
  • w/ with
  • b/c because

PS: Are there similar abbreviations that are commonly used?

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    Other variations for because observed in the wild are: "cuz", "bc", "cos", "cause", "coz", "b'caz", "bec.", "bcoz" and "bec". Commented May 30, 2013 at 20:59
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    I have seen w/o, b/c, and w/ in US contexts in non-formal writing (especially email and business memos). Commented May 31, 2013 at 20:16
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    My recommendation: use them only when you lack time or space to write them out fully.
    – GEdgar
    Commented Jun 1, 2013 at 14:59
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    If your lovely minds are available, could you please help with a related question I recently posted? Is there a common abbreviation for “with or without”
    – evan.bovie
    Commented Aug 21, 2020 at 22:18

7 Answers 7


Both "w/" and "w/o" were common, very informal, U.S. abbreviations in correspondence, and in tight spots on data tables, until recently. "C/o" has always been used in addressing letters to third parties: "John Jones, c/o Smith family..."

The other "slash/shilling mark" abbreviations were so uncommon that they usually were not used because of lack of clarity.

I personally use only "c/o", "w/" and "w/o" of all the abbreviations shown on this page. (Except for very limited use of the technical jargon abbreviations: I/O, A/C.)

  • Thanks for your answer, but I have some difficulty in understanding what you mean with shilling in "slash/shilling mark"?
    – rena
    Commented Jun 1, 2013 at 7:35
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    @rena Shilling An amount of currency like "three shillings and six pence" was written 3/6.
    – Andrew Leach
    Commented Jun 1, 2013 at 11:01
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    c/o stands for care of.
    – bib
    Commented Jan 25, 2014 at 20:46
  • en.wikipedia.org/wiki/Slash_%28punctuation%29#Abbreviations says the slash is British in origin
    – endolith
    Commented Nov 11, 2014 at 17:06
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    Hey I got an email from recruiter saying, I will show it to my contact at W/O and get in touch with you asap What does W/O mean here? Commented Jan 3, 2018 at 8:43

English writing often uses slashes to form two-letter abbreviations, plus the one-letter w/ – some examples, roughly in order of frequency:

  • I/O – “input/output”
  • w/ – “with”
  • c/o – “care of”
  • A/C – “air conditioning”
  • w/o – “without”
  • R/C – “remote control”
  • b/c – “because”

Like most abbreviations, these are less common in formal writing, although some of them (like I/O) appear often in technical writing. Some are uncommon even in informal writing; I've only seen b/c in things like text messages and tweets, for example, and those usually leave out the slash.

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    Is this more a U.S. thing? As far as I can recall, I've not seen A/C (if I did, I'd think it meant alternating current), R/C, nor (as mentioned in my answer) w/ & b/c.
    – TrevorD
    Commented May 31, 2013 at 23:57
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    This Ngram for British English shows that I/O, w/, and c/o are about as common as in American English, but the other ones are less common. Wikipedia has a cryptic comment that “British English in particular makes use of the slash instead of the hyphen in forming abbreviations.” Hyphen? Commented Jun 1, 2013 at 0:16
  • Thanks Bradd. I purposely didn't mention I/O & c/o in my previous comment as I was aware of those. In particular, c/o has been used as long as I can remember. But otherwise this suggests I was roughly correct. Of course, it doesn't indicate what the abbreviations meant (e.g. A/C - see prev. comment.) I suppose also that w/o would show up as both w/o & w/?
    – TrevorD
    Commented Jun 1, 2013 at 11:09
  • Thanks. This is really helpful for non-English speaker. I like to collect some abbrs for fun. :D
    – p3nchan
    Commented Sep 16, 2015 at 15:54

I would say all three are fairly common, though not necessarily "correct".

I think almost everyone will understand all of them, but I would avoid them, particularly in formal contexts. Of course in personal note-taking you can use whatever shorthands you like. 

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    "almost everyone will understand all of them" where? In the US or elsewhere?
    – TrevorD
    Commented May 30, 2013 at 18:30
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    @TrevorD I am from the UK and so most familiar with UK usage, but I'm pretty sure I've seen all these used by US speakers too and would be surprised if native speakers from other regions didn't understand them.
    – Caesar
    Commented May 30, 2013 at 18:31

Along with TrevorD, I'm in the UK.

I've seen w/o for without and w/ for with, but not b/c.

They are not suitable for formal use.

It's potentially of interest that the Pitman shorthand symbol for w resembles w/ and is often used on its own to mean with.

Pitman symbol for W


I can't answer for what is common usage in the US, but in the UK:

  • I've seen w/o for without
  • I don't recall ever seeing w/ or b/c

I certainly wouldn't say that they are in common 'public' usage, and would suggest they are best reserved for private usage, note-taking, etc.


Abbreviations used for taking notes or in other instances where abbreviations might be acceptable. I use them when correcting answers on tests sometimes since there is frequently a scarcity of space.

In terms of usage, you might perhaps consider the word "and" and when you would use either & or + to indicate it. If either of those is too informal for a situation then it would probably be better to spell out without than use the abbreviation.


I also use w/ for with, when, where, what, why,and who. Depending on the context it can be easily deciphered. In addition, I use "btw" for between, and o/s - i/s for outside/inside.

  • 2
    Honestly, I've never seen w/ used for anything but with. And it would probably confuse the heck out of me if I saw it. Do you have a source for that indicates this usage is used by anyone else? And in modern Internet speak, "btw" is regularly used for "by the way". Ditto "o/s" is used for Operating System. I'd be careful about using those unless they were clearly unambiguous.
    – Nick2253
    Commented Nov 11, 2014 at 15:50

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