GTF: the GPL'ed TLA FAQ

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z / All / Stats

If, like me, you run into lots of three-letter abbreviations (TLAs), you may want to refer to the GPL'ed TLA FAQ (GTF). Originally the product of a 2001 drinking binge with Bart Samwel, this is a list (in minimal plaintext format) of tens of thousands of known TLAs and their meanings. Here you can find the meanings of cryptic and often unnecessary TLAs such as GNU, GTF, and FAQ. Never again utter the words "WTF? OMG, YAT!" in vain.

The GTF is being made available under the GNU General Public License (GPL) as defined by the Free Software Foundation, hence the name.

The GTF has moved here

This project previously lived on my xs4all.nl home page. However that service is being shut down, so as of 2026, its home page lives on pqxx.org.

The list itself is maintained on GitLab.

What TLAs belong in the list?

The TLAs in this list are not explained any further, nor will you find any reference to their origin. This was a deliberate choice. The GTF is not an encyclopedia. It keeps the threshold to contribution low.

That's not to say that I'll accept just any TLA. All entries get vetted by hand, but they also have to pass some automated checks for obvious mistakes, duplicates, and near-duplicates.

Here are some of the criteria:

  • A TLA consists of three letters. No ampersands, no exclamation points, no slashes, and no digits. Abbreviations like IE3, B2B, B2C, P2P, and 3M are no good. Nor are AT&T, B&B, or OS X. I accept lower-case letters, but in the list they turn into upper-case ones.
  • If the usual abbreviation doesn't fit the GTF format, but there's a variant that does, I'll take the variant.
  • Abbreviations must span multiple words. This gets a bit hazy with the habit of including spaces in English compound nouns, so sometimes I'll use it as an excuse to include a highly popular TLA. A hyphen somewhere between different parts is good enough, but e.g. ACK for Acknowledgement is not getting in. (This is also why you won't find TNT here: it stands for TriNitroToluene.)
  • The TLA's initial letters don't have to be right at the beginning of their respective words, so long as they come from different words.
  • The three letters in the TLA don't all have to be in the meaning. Words like "cross" and "trans" are often abbreviated to an X. Which helps fill out our coverage of the total TLA space very nicely.
  • If not all the letters from the TLA are in the meaning, we add a bracketed exclamation point to the meaning: [!].
  • For a TLA to be included, either it must be commonly used in the English-speaking world, or its meaning must be in the English language. This is why BMW (Bayerische MotorWerke) is included, but HSV (Hamburger SportVerein) is not. It's an arbitrary choice, and by the terms of the GPL, anyone who is dissatisfied with my choices is free to fork off their own version of the list.
  • The list is in ASCII. Any diacritical marks we transcribe in standard ways where possible, or we drop them. Thus "café" becomes "cafe" and "müsli" becomes "muesli"... I have no idea how to transcribe the Spanish "ñ", but luckily the Spanish language does not seem to have contributed much to TLA culture. Well done, Spanish!
  • Before you ask: I consider "KGB" in English an abbreviation of a transliteration, not a transliteration of an abbreviation, so it just barely made it in. The real reason for this is that it's far too popular to omit.
  • If there is an official definition, I don't want accidental variations. There are incredible numbers of mistaken meanings out there, usually substituting cliché TLA words for more sensible words: "Unicode Character System" instead of the correct "Universal Character Set," "Video" instead of "Visual," etc. Inevitably some of these mistakes will sneak in.
  • Jokes and parodies are accepted without qualms. Mothers Against Canada (MAC) was invented for South Park: Bigger, Longer, and Uncut. No problem. WAP didn't really stand for Where Are the Phones, but back in the late 20th century, it might as well have. Both definitions (the official one is Wireless Application Protocol) are welcome as long as they are actually used somewhere. Once is enough, assuming it wasn't done just to get it included here. Yes, that happens.
  • Names are allowed. Companies, famous people, underground movements whether real or fictional, landmarks, universities... send 'em in.
  • I'll accept some clarifying additions in the meanings, written in [square brackets]. This is mainly for conspicuous omissions though, as in the "Centers for Disease Control [and Prevention]" (CDC). Minor clarifications are allowed, e.g. "[Microsoft] Windows" avoids confusion since "windows" is a generic term in computing but is being used as if it were a trademark. The general rule is: try to keep these additions shorter than your name. Naturally my friend Al Al is exempt from this rule.

The List

You can view the GTF directly in plain text. There are also smaller lists, broken down by the first letter:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Latest statistics

REST APIs

Kirit Sælensminde has created an API and Web UI for querying the GTF.

Henk van Voorthuijsen created an API for querying, vetting, and uploading TLAs, as well as finding missing ones. Sadly, Henk suddenly passed away on 2023-03-05. We still miss him!

Oh, and at one point... Know those "URL shortening" services on the internet? You feed in a URL and they give you a shorter one that points to the same page? Wichert Akkerman once built one that stretched your URL, making it look bigger and more important. One of the ways of doing that was to expand each 3-letter sequence as a TLA. I don't think it's still around, sadly.

Contributing

If you have TLAs or corrections to contribute (please check them carefully first though!), please submit them as work items or merge requests on the GTF GitLab project.

GTF Contributor Program

If your TLA gets included in the list, you may copy the GTF contributor logo and display it on your home page or website to show that you're a contributor.

GCP logo

Congratulations! This makes you a member of the GTF Contributor Program, or GCP for short.

Authors

The GTF was originally conceived in 2001 by Bart Samwel and Jeroen T. Vermeulen. The latter maintains it to this day.

Henk van Voorthuijsen, besides writing his own tooling for querying and contributing TLAs, also made it his mission to fill out TLA Space. That is, he sought out TLAs for letter triplets that were not covered in the GTF yet.

Frequently Asked Questions

Are you serious!?

Who can tell? It works either way.

And speaking of "serious"... Do you call this a website?

It's a minimal port of what I started writing in raw HTML in the year 2001. Sprucing it up hasn't been a priority. But... if you have creative ideas, feel free to build your own UI, or submit work items on the GitLab page!

What's the most common TLA?

See the separate little generated statistics page. At the moment I'm writing this it's "CSW" (with well over a hundred meanings), but it hasn't always been. For a long time it was "ACE."

What is "TLA Space"?

That's the space of all possible triplets of upper-case ASCII letters.

TLA Space is fixed at 26 * 26 * 26 == 17,576 entries.

How many TLAs have meanings? How many still have none?

More than half of TLA Space is covered by at least one TLA, but nowhere near all of it.

For up-to-date stats, see the generated statistics.

Fun fact: we have enough different meanings that each unique combination of 3 letters could easily have at least 1 definition. But they're not distributed evenly... Statistics are funny that way.

Hey, let's have a list of 4-letter abbreviations!

I'd love to, but who has time? And mathematically, there could be a lot more 4-letter abbreviations ("ETLAs") than 3-letter ones.

But here too, if you feel motivated to do it... Please do.

Why are the statistics so poorly presented?

Because they are generated by a small script.

Who knows, perhaps one day I'll make something nicer. But if you like the GTF you can also write your own front-end for it, as some have done. What would be the fun if I made everything nice and shiny and complete?

What tools do you use for maintaining this?

I like to stay close to the metal, keep things simple, not lose sight of what's going on under the bonnet.

So you probably won't be impressed by my tools:

What's this story about Donald Knuth?

I mis-spelled his middle name in his entry in the list. It's Ervin, not Erwin. He had someone email me to correct it. I am honoured and embarrassed.