[JackFr]

It’s shorthand for “in context, that might not mean what you think it means.” I would use term of art to distinguish something that has a particular meaning for the context. For example “clobber” has a useful meaning, a meaning that many people use, but when programmers use it, it’s a term of art that means something specific and non-obvious.

[yesenadam]

Yes..it's a term in programming, a programming term.

None of these replies justifying "term of art" seem at all convincing to me. "Term doesn't imply a specialized meaning" – but I think it does here: if "clobber" didn't mean something different in programming, you wouldn't (need to) say "it's a programming term". "It's a programming term" precisely means "the term has a meaning in programming different to what it commonly means". The listener already knows it's a word in everyday English, which is apparently all "term of art" adds.

[lanstin]

To my ears, "term of art" has a certain connotation of precision that the alternatives lack. Not just "this means something you might not guess" but "it has a very particular, well-defined meaning you might not guess."