Huh, lemme do it.

Schelling fence → bright-line rule

Semantic stopsign → thought-terminating cliché

Anti-inductiveness → reverse Tinkerbell effect

"0 and 1 are not probabilities" → Cromwell's rule

Tapping out → agreeing to disagree (which sometimes confuses LWers when they take the latter literally (see last paragraph of linked comment))

ETA (edited to add) → PS (post scriptum)

That's off the top of my head, but I think I've seen more.

Has anyone put together a translation dictionary?

It was many times debated on LW whether LW needlessly invents new words for already existing terms, or whether the new words label things that are not considered elsewhere.

I don't remember the outcomes of those debates. It seems to me they usually went like this:

"LW invents new words for many things that already have standard names."
"Can you give me five examples?"
"What LW calls X is called Y everywhere else." (provides only one example)
"Actually X is not the same concept as Y."
"Yes it is."
"It is not."
...

So I guess at the end both sides believe they have won the debate.

I just ran into this one because it became used in a reddit thread: in this post Eliezer uses the term "catgirl" to mean a non-sentient sexbot. While that isn't a traditional rationality term, I think it fits the spirit of the question (and predictably, many people responded to the Reddit thread using the normal meaning of "catgirl" rather than Eliezer's.)

Previously.

RationalWiki discusses a few:

Another problem of LessWrong is that its isolationism represents a self-made problem (unlike demographics). Despite intense philosophical speculation, the users tend towards a proud contempt of mainstream and ancient philosophy[39] and this then leads to them having to re-invent the wheel. When this tendency is coupled with the metaphors and parables that are central to LessWrong's attraction, it explains why they invent new terms for already existing concepts.[40] The compatibilism position on free will/determinism is called "requiredism"[41] on LessWrong, for example, and the continuum fallacy is relabeled "the fallacy of gray." The end result is a Seinfeldesque series of superfluous neologisms.

In my view, RationalWiki cherry picks certain LessWrongers to bolster their case. You can't really conclude that these people represent LessWrong as a whole. You can find plenty of discussion of the terminology issue here, for example, and the way RationalWiki presents things makes it sound like LessWrongers are ignorant. I find this sort of misrepresentation to be common at RationalWiki, unfortunately.