You see it every single day. It sits right there at the start of your inbox, clogging up subject lines like digital lint. RE: Meeting Notes. RE: Regarding that invoice. We use it so much that it has basically become invisible, a tiny linguistic ghost haunting our communication. But if you actually stop and ask most people what "RE" stands for, you’ll get a shrug or, more likely, a confident but totally wrong answer.
Most people think it means "Reply." It makes sense, right? You hit the reply button, the little letters pop up, and life goes on. Others, usually those who want to sound a bit more formal, will tell you it stands for "Regarding."
They’re both wrong. Well, mostly.
The truth is actually buried in centuries of legal tradition and a dead language that still dictates how we talk to each other in the 21st century. It’s a bit weird when you think about it. We’re using high-speed fiber optics to send messages encoded with Latin abbreviations used by medieval scribes.
The Latin Root Nobody Remembers
The term "RE" is actually a take on the Latin word res, which translates to "thing" or "matter." In the context of a letter or a legal document, it is the ablative case, re, meaning "in the matter of" or "concerning the thing."
Lawyers have been using this for ages. If you look at a court case title like In re Smith, it literally means "In the matter of Smith." It wasn't meant to be an abbreviation for "regarding," though the meanings overlap so much that the distinction has basically dissolved over time. It’s one of those "correct vs. common usage" battles that common usage eventually won by a landslide.
Back in the days of physical typewriters—and long before that, when people used quills—secretaries would type "RE:" followed by the subject of the memo. It was a formal pointer. It told the reader, "Hey, this is what this specific piece of paper is about." It was a filing tool.
Then the internet happened.
When the early architects of email were setting up the protocols we still use—specifically RFC 822 and the later RFC 2822—they had to decide how to handle threads. They didn't invent "RE" out of thin air; they just dragged the existing office culture into the digital world. The engineers decided that when you replied to a message, the software should automatically prepend the subject line with those two letters.
Why Everyone Thinks It Means Reply
It is a classic case of "backronym" energy.
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Because the "RE" prefix only appears when you respond to someone, the mental link to the word "Reply" is almost impossible to break. It’s intuitive. If I hit reply and "RE" appears, my brain completes the circuit. Even some modern email clients have leaned into this, treating it as a functional UI element rather than a piece of text.
But here is the kicker: if you are writing a brand new email from scratch and you type "RE: Question about the dog," you aren't replying to anything. You are using the original Latin sense—you are starting a conversation "concerning the matter" of the dog.
Language evolves. Honestly, if 99% of the population thinks it stands for "Reply," does the Latin origin even matter anymore? Linguists would call this a "functional shift." In the world of tech, it’s just a legacy bug that became a feature.
The Unspoken Rules of Email Etiquette
Since we’re talking about what "RE" stands for, we should probably talk about how people absolutely ruin it. We’ve all seen those email chains that look like this:
RE: RE: RE: RE: RE: RE: Pizza Friday?
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It’s a nightmare. It makes the subject line unreadable on mobile devices. Most modern email services like Gmail or Outlook are smart enough to collapse these now, but older systems or mailing lists still struggle.
There is also the "Subject Line Hijack." This is when someone takes an old email with a "RE:" in it and sends a totally unrelated message because they were too lazy to find your email address in their contacts. Suddenly, you get an email titled "RE: Q3 Budget Report" but the body of the email is just "Hey, did you leave your umbrella at my house?"
Don't do that. It breaks the "matter" of the "RE."
RE vs. REF vs. FWD
People get these mixed up constantly.
- RE: Concerning the matter (Latin: in re).
- REF: Reference. This is usually used in business for a specific ID number, like an invoice or a tracking code.
- FWD: Forward. This isn't Latin; it's just a blunt abbreviation for sending someone else's mail to a new person.
In legal circles, "RE" is still treated with a level of gravity that your average office worker wouldn't recognize. If a lawyer sends a letter with "RE: Estate of John Doe," that prefix is doing heavy lifting. It’s defining the legal scope of the communication.
Is RE Going Away?
Probably not.
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We’ve tried to replace it. Slack and Microsoft Teams use "threads" which get rid of subject lines entirely. But email is the cockroach of the internet—it will survive everything. And as long as we have email, we will have those two little letters sitting at the front of our messages.
It’s kind of cool, in a nerdy way. Every time you send a boring email about a TPS report, you are participating in a linguistic tradition that dates back to the Roman Empire. You’re basically a digital centurion. Sorta.
How to Handle Your Inbox Better
If you want to be the person who actually uses "RE" correctly (or at least efficiently), here is how to handle it without annoying your coworkers:
- Clear the Clutter: If a thread has gone on for more than 10 emails and the topic has changed, delete the "RE: RE: RE:" and just write a new subject line. Your colleagues' eyes will thank you.
- The "No Subject" Sin: Never send an email without a subject line, but also don't just put "RE:" with nothing after it. It’s the digital equivalent of walking into a room and just saying "Regarding..." and then staring at everyone in silence.
- Legal Context: If you are in a formal or legal setting, remember that "RE" is a pointer. Use it to reference specific case numbers or project codes to make filing easier for the person on the other end.
- Stop the Hijack: If you’re starting a new topic, start a new email. Don’t lean on an old "RE:" thread just because it’s convenient. It messes up the search functionality for everyone involved.
Basically, "RE" stands for a lot more than just two letters. It’s a bridge between ancient law and modern tech. Now that you know it’s Latin and not just a "Reply" tag, you can be that person at the office party who corrects everyone. Or, you know, maybe don't do that if you want people to keep talking to you.
Next time you see it, just remember: you're not just replying. You're addressing "the matter." Keep your subject lines clean, keep your threads organized, and maybe give a little nod to the Romans for giving us a way to organize our digital chaos.