I believe there’s a three-word phrase that means “a specific piece of jargon, used in a different sense than it’s normal meaning.” It’s something like word of practice or word of field. It feels more formal than jargon. I think it specifically means a word that has an ordinary meaning that is being disregarded, not just any technical word.
- Hardness here is a ____ of ____; in geology it specifically refers to measuring which minerals can scratch which other minerals.
- End of day is a _____ of _____ at [company]; it always refers to 4pm Eastern Time when the stock market closes.
It might be a French loanphrase—my brain is supplying me with nom de plume, which obviously isn’t correct.
My best phrase right now is “technical word/phrase” (too general) or just describing it as “used in the domain-specific sense”.
(Searching for “jargon synonyms” doesn’t get me there, “singular jargon” doesn’t help, and “technical word synonyms" just gives synonyms for technical.)