If you’re writing cover for mass movements? Run it by someone else first.

If you’re talking to people? Don’t dumb it down. Just be open to explaining words and concepts. People like to learn. Provided you aren’t being condescending or gatekeepery, it’s not a problem. (Unless you talk like Zizek or Jameson, in which case, don’t.)

Actually, Jameson and Fisher provide pretty good contrasting examples. Jameson came up with the idea of postmodernism as the cultural logic of capitalism (in the book of the same name), whereas Fisher built upon it with the notion of Capitalist Realism (again, in the book of the same name). Try reading both of them, and you’ll very quickly get an understanding of what accessible language does and doesn’t look like.

Here's a great tool if you are trying to reach the largest audience possible.

If you are speaking or writing above a 5th grade reading level, you are alienating a lot of people.

Specialized language has its place, but fluency at various reading levels is a great skill to have.

It's okay to use academic language if you're explaining it. If you replaced "intersectionality" with "flibertygoop" everywhere in your writing, would a reader still come out of it understanding flibertygoop? Then you're fine, you've explained the thing. That's particularly important for words that have many colloquial (or even formal) meanings, like socialism or anarchy, since it might already be flibertygoop to your audience.

It's also worth considering are how google-able the term in question is. If you start talking about intersectionality, that's a unique word and if someone trips over it they can find an answer easily. If you start talking about the absurd, you're going to want to name-drop Camus or something, since that's just a common word in English.

Finally, not every message needs to be accessible. If you can safely assume your audience knows the thing you're talking about, just use the jargon and save some time.

Practice, exposure to people who speak in a more normal way. I have the opposite problem, I always describe stuff in plain English, and highly educated types tend to find it really funny hearing me talk about complicated academic subjects in a way they are not used to.

To make myself stand out less and be taken more seriously by these kinds of people, I practice explaining things in my head when I'm doing boring stuff like cleaning around the house. Like, just pick a subject and start lecturing about it. Even if it's a little incoherent and badly structured, it's practice.