As others said, with as w/ was around as part of secretarial shorthand, which got taught to most people keeping corporate documentation and it stuck.

There are a lot of abbreviations like that in the English language that came from abbreviations in written form due to the media in was written in, whether it was newspapers, telegraph, handwritten shorthand, or computer based. It may not make sense because English isn’t a language designed to make sense; it isn’t even designed.

Pretty sure it started w/your mom

Some various answers here; but for me, it came from w/o as a shorthand for ‘without’, then I started sometimes writing w/ for ‘with’ and wondering if that’s okay!

In spanish we use the same abbreviation: c/ for “with” ans s/ for “without”

My guess is these became common with the telegraph. Since messages were expensive and the sender paid by the letter, abbreviations where commonly used to keep messages short.

It comes from the letter “w” as in, “with”

w/ appears to have origin in the food industry some 70 years ago (according to this question).

To me it makes sense, as I first encountered it in video games where abbreviations, acronyms, and text-saving-slang are commonplace. Furthermore, while abbreviations usually have multiple letters (in written text, not physical or mathematical equations), single letter abbreviations can quickly become confusing, so I belive that this is the reason for putting a slash behind it, or possibly a bar above it.

RANT: While I know that language changes all the time, I find it very unfortunate that this little fellow o/ and possibly his slightly more formal friend o7 have become synonymous with “nazi salute”. First off, it’s the wrong arm! And second off, what do you have against “man waving” and “man saluting”?

It must be very confusing for someone who uses this newer definition of o/ to visit the Elite:Dangerous forums.

EDIT: I’m very happy that I apparently am the only one who has met people who don’t know the real meaning of o/ and o7. I feared that this was a widespread problem, but luckily it appears that I simply am a worrywart.

I know this isn’t an answer on the topic of the history of abbreviations, but I found this page to have a useful list of abbreviations with the foreign speaker in mind.

I use c̅ for with and s̅ for without, these may make more sense for you depending on your native tongue. They are medical shorthand.

No idea, but it might be connected with shorthand, which was a common and sophisticated note-taking technique that allowed people, mostly secretaries in business, to write as fast as talking.

If that annoys you, never get into advanced maths. There’s arbitrary symbols that make no sense like 3 dots in a triangle means therefore. An upside down capital A means for all.

Back when business was done entirely by paper, you’d have catalogues, books full of tables of things you could order with their prices. You have limited space for printing item names and those abbreviations were used there (e.g. in the 1920s).

Writing by hand it’s fast, and visually creates a space to answer “with what?”

People have needed quick notations for as long as language has been written. While I’m not going digging for links because fuck that shit for a casual comment, it remains true in every form of writing around the world that I’ve read about (obviously, I can’t read them all, and the few I can I don’t read well, but that’s why linguists get paid to do it for a living).

There are numerous symbols that represent entire words in writing. $, &, @,®,©,™, and that’s just the few my on screen keyboard makes easy.

The / is very commonly used to denote that the rest of a word has been “slashed” off of the previous section. It is intuitive to a degree in that it has been used for that in multiple places independently. Using a single symbol for that is very common.

It happening with with is just the most common example that most people will run into. Moreover, it’s typically applied in situations where the expected readers will be aware of that shorthand.

As an example, one of the nursing homes I worked at used a letter slash system for a lot of the common tasks we’d perform on our big whiteboard. You’d have room numbers and letters (for two bed rooms), with a grid. If you gave the patient their shower, you’d note s/. Bed bath would be b/. Meals were denoted with the first letter and slash except breakfast, which got m/ for morning (because b was already taken).

Now, we used lower case for tasks and upper case for initials as well, so that you could come up between rooms, make the note, and sign it in just seconds. When you’re taking care of 30+ patients per hall, those seconds are valuable.

The w/ notation has been used for hundreds of years that I know of. I saw copies of colonial era logs that used it, and they went back to the 1600s iirc.

But, let’s give another example to help you get that it’s really no different from another word that happens to mean the same thing as with. If I say something is big, you’ve probably seen the word before, right? Picking up English as a second language usually means starting with smaller adjectives.

But, there’s other words that mean the same thing, or the same thing at a different scale large means the same as big. Huge means the same basic thing, but is typically used to mean “very big”. So, huge is a kind of shorthand too, in use. But until you encounter it the first time, it’s no more intuitive than big.

Then, the glory of English means we get all kinds of surplus words. Gargantuan, brobdingnagian, massive, they all mean that something is very big.

So, just think of w/ as a very small word that happens to share a single letter with the word with, and you simply hadn’t run across it. Nobody has the entirety of English in their heads, even vocabulary geeks. We all eventually run across something new to us, though the longer you read in English, the less often it occurs.

Now, why the slash? As opposed to some other symbol like -, :, or whatever. Think about writing with a stylus, brush, or quill pen. Dots and slashes are the easiest things to write, and are thus the fastest.

If you’re on a dock, scribbling down the load that’s coming in, you need that speed. When you’re keeping log books of any kind, you need to minimize hand strain, so fewer symbols means less strain.

W/ is the OMG or lol of more important things. It’s just another way of saving space and/or time

University shortcut. When you have to take notes on paper so damn fast, you develop techniques. Those techniques get shared around. That’s how it was explained to me.