Jargon is a membership test

For a couple of years I ran corporate finance across several business units through a run of acquisitions, and in those rooms I was the person who had the vocabulary. Then in 2025 I moved into technical delivery and became the person in the room who did not. Roughly the same seniority, opposite side of the glass.

Being on both sides within a few years is the only reason I have anything to say about this. From one side, specialist vocabulary is obviously precision. From the other side it is obviously exclusion. Both of those are convincing from where you are standing and neither is right.

The four second test

Here is the only test I have found that works. Say the plain version. If the plain version loses information, the term is real. If the plain version is just longer, the term is a password.

Take an accrual. The plain version is something like: a cost that belongs to this month even though nobody has sent us a bill and no money has moved. That is twenty words against one, and more importantly the twenty words are where people go wrong. Half of them will hear it and still book the cost when the bill arrives, because the plain sentence carries the concept without carrying the discipline. The word does work the sentence does not do. It is a real term.

Now take almost anything that sounds like it belongs to a management deck. A thing being in flight. Bandwidth. Alignment. Substitute the plain version and nothing whatever is lost. Not a nuance, not a caveat, not a boundary condition. The plain version is shorter, in several cases. Those words are not carrying information, they are carrying evidence that the speaker has been in rooms like this one before.

The reason I like this test is that it does not require you to know the field. You can run it as a newcomer, out loud, in the meeting. Ask what the plain version would be. If it comes back instantly and the term survives, that is a term. If it comes back with irritation, that is the membership function defending itself, and you have learned something about the room rather than about the word.

The part I got wrong, and did myself

I spent a long time as a plain-language absolutist about this, and I was wrong in a way I only noticed by doing the opposite.

When I arrived in delivery I learned the vocabulary fast. Faster than I understood the underlying concepts. I could use the words correctly in a sentence a good while before I could have defended what they meant, and it worked, in the sense that people stopped explaining things to me and started including me in the disagreement. That is the membership function, and I ran it deliberately, and I would do it again, because the alternative was another six months of being explained to.

Which means the criticism has a floor under it. The vocabulary is not only a gate, it is also the fastest available proof that you have done the reading, and in a room where nobody has time to test you properly, a cheap proof beats no proof. Refusing to use the words is not neutral. It reads as either ignorance or as a kind of performance, and both cost you standing you then need for something else.

So the honest position is not that jargon is bad. It is that most rooms are running two functions through one channel, and the same word is doing precision for two people and identification for the other six, and nobody has any incentive to separate them.

The tell that stayed with me

The people I have trusted most in both fields had a specific habit. They would use the term, and then, without being asked and without any change in tone, say the plain version immediately after. Not as a definition. As a second attempt.

It costs them four seconds and it gives away nothing, because anyone who already knew simply hears a restatement. I noticed it long before I understood what it was doing, which is answering a question nobody in the room is willing to ask.