not available is not not/available, and not applicable is not not/applicable.

Why is it n/a?

4 Answers 4


The important thing to note is that these abbreviations are much more common in handwritten correspondence than they are online. c/o is often used when addressing post to someone via a third party, and w/ and w/o are common written shorthand for with and without.

It was quite common in older written texts to abbreviate words using some identifying letters and a line, for example:

  • w— for with
  • D—r for Doctor, which eventually became just Dr.
  • Rev—d for Reverend, which became Revd or Rev.

These are part of a long history of written abbreviations that are just a bit awkward in print. I would guess that printing a slash in these abbreviations arose simply as a way of representing the shorthand that people had already been using in writing for ages. Using a diagonal slash-like mark (c/o) is just narrower and faster to write than something like c—o—, which looks awkward.

  • 2
    I've seen where Lieutenant Colonel was shortened to Lt/Col and similar abbreviations for other military ranks. I'm not sure if this is too common these days, however.
    – HorusKol
    Commented Feb 14, 2011 at 12:50
  • I would not say that these abbreviations are not common online. Especially w/ and w/o can often be seen on Twitter.
    – rugk
    Commented Jan 10, 2017 at 22:20

As always, medieval palaeography to the rescue! In medieval cursive, a great variety of spellings, punctuation marks, and diacritical marks were used; you wouldn't believe how inconsistent even a single document could be. There were dozens of abbreviation and contraction marks in use, which were reduced gradually as the European languages became increasingly uniform over the centuries.

A diagonal line was for a long time universally used to truncate words: my estimate would be that it was in use at least between 1200 and 1800, possibly much longer. I suspect that this is the origin of the diagonal line used in these modern multi-word acronyms or abbreviations.

As far as I know, it was not used in exactly the same way; that is, it was usually written as a long downwards continuation of the final stroke of the truncated word, or as a strike through the final stroke (see below): but the modern form can very well be ascribed to the limitations of the printing press. The same mark can be found in many other modern languages too, like Dutch v/d (van de), t/m (tot en met), etc, in which it feels no more logical than in English. That we chose certain marks over others in certain contexts probably happened more or less at random for a large part.

http://inkunabeln.ub.uni-koeln.de/vdibProduction/handapparat/nachs_w/cappelli/cappelli.html enter image description here


Lowercase abbreviations require punctuation to distinguish them from words like na, as opposed to uppercase abbreviations, which are understood not to be words in and of themselves because words are not capitalized in sentences.

  • But N/A is also common. Even more common than NA. (en.wiktionary.org/wiki/n/a)
    – user3812
    Commented Feb 14, 2011 at 3:29
  • 2
    @Dante n/a is more etymologically correct—both not and applicable are not proper nouns. Thus, I would conclude that N/A evolved from that, and that's why the slash remains in the uppercase form.
    – waiwai933
    Commented Feb 14, 2011 at 3:32
  • 1
    Yeah, but that raises the question of why we went with, predominantly, n/a rather than n.a.
    – chaos
    Commented Feb 14, 2011 at 3:37
  • 4
    @waiwai933: Not really, since periods for the purpose seem standard to me and the idea of using a slash seems to come out of nowhere.
    – chaos
    Commented Feb 14, 2011 at 3:43
  • 2
    @chaos Not necessarily— c/o, w/o, y/o, a/c
    – waiwai933
    Commented Feb 14, 2011 at 3:56

It's nonsense relic from an old day, NA should be used even though Meriam Webster says N/A is correct. The logic was they were afraid na would be misread as no to often, which in itself is a silly jusifications today because we capitalize abbreviations.

For letters to grandma, who cares, but this all has serious implications in the modern world. N/A, anything with a slash really, possess a potential issue to security and functionality in coding and most people today read that as "not over or divided by applicable".

Thus, N/A is dead.

  • Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.
    – Community Bot
    Commented Oct 3, 2022 at 17:37
  • It is not clear what this answer adds to the very detailed answers that were posted more than a decade ago.
    – jsw29
    Commented Oct 4, 2022 at 16:11
  • jsq29: It provides a justification for why the standard has changed, even if Merriam Webster hasn't caught up. Ultimately, language is fluid even though some consider it sacred. Thus, slash was once used in place of dot for abbreviations, the letter s was once written as f, just some examples. Language is always defined by the people that speak it and the references only end up referencing us... so I don't see the value of a reference here, because there are always counter references to every answer in the real world. Thus, lets see who has the most votes in 100 years =)
    – gunslingor
    Commented Oct 12, 2022 at 14:38

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