[citizenkeen]

A lot of things are jargon that are not terms of art. When I was practicing law, a lot of people in my legal circles would jokingly refer to their spouses as their "domestic associates". That's not a term of art, but it is lawyer's jargon or an idiomatic expression.

[westoncb]

That’s an interesting example, though I read it as a kind of parody of jargon rather than actual jargon. It’s a tricky case though since jargon also has multiple senses and your classification fits one of them.

I’m curious whether you would consider “domestic partnership” to be both jargon and a term of art (I would).

It’s interesting reviewing definitions of ‘jargon’: while you do find things like e.g. “ specialized technical terminology characteristic of a particular subject” —mostly you find references to incoherent/nonsensical speech.