I am a sucker for "knowing the exact term for a phenomena, a process, etc in a technical environment".
Jargon is probably not a good word since it's too casual, and probably disapproving.
It describes a set or system of names or terms. As in the particular science or art's correct names.
I would go with terminology, as you said. Or vocabulary.
Terminology: n. The body of terms used with a particular technical application in a subject of study, theory, profession, etc.
Vocabulary: n. Words used on a particular occasion or in a particular sphere
Lingo would also work, although it is also colloquial and not as formal.
Lingo: n. The vocabulary or jargon of a particular subject or group of people
I would use lexicon in this place to refer to what you're calling an "environment".
- the vocabulary of a particular language, field, social class, person, etc.
That, in my opinion, is a better fit than "jargon", which commonly connotes the confounding elements of a certain group's vocabulary.
I like "nomenclature" for this purpose, which is very close in definition to "Terminology":
Per definition 3a in Merriam-Webster Online:
Nomenclature: 3a: a system or set of terms or symbols especially in a particular science, discipline, or art
Example: "A directory and nomenclature of the first aeroplanes, 1809 to 1909" - Charles Harvard Gibbs-Smith, Science Museum (Great Britain) H.M.S.O., 1966
I would go with "precise technical term" or "precise technical definition".
What is the precise technical definition of hard real-time?
Precise, because that conveys the idea a bit better than exact.
Technical, because you don't want the dictionary definition, but rather the current technical usage.