On: Great Vowel Shift

[aesh2Xa1]

"Jargon" is a good word for this case.

[shemtay → aesh2Xa1]

"Jargon" sounds pejorative to me, and implies that the phrasing is difficult for outsiders to understand.

"Term of art" only implies that it is the specific phrasing used by practitioners to describe the matter at hand.

[anoncake → aesh2Xa1]

Does that imply that the meaning is well-defined like "term of art" does?

[aesh2Xa1 → anoncake]

Yes, it requires that the idea is defined in a concise way that is professionally/contextually restricted.

Use "term of art" if you'd like. I think "jargon" is a commonplace alternative and I like it.