A technical term is a term that has a specific definition within the used context. This is different than a non-technical term which is often relative, and defined culturally. In some cases there is a “turtles all the way down,” recursive sort of issue where technical terms break down but for the most part they exist pretty well defined for their use cases.
As an example, what’s a “big” number?
- For a kid the number 100 might be big
- For a cryptographer, the number might be big
- For an astrophysicist, the unit makes all the difference (1 inch is small but 1 AU is relatively big) In all these cases there’s no agreement even among people within the group what “big” is. For a certain application a number might be “big enough”, but does that mean it’s big?
A “prime” number is a technical term because there is an explicit definition of what it means for a number to be prime: it has no factors except for one (1) and itself. A prime number means the same thing to a kid as a cryptographer and probably for the astrophysicist. However, it might not have as much meaning to the latter.
Additionally, primeness is specified within its domain. Here, a prime number is well defined, but a planet that is a “prime choice” for exploration doesn’t have the same primeness as the number 17.
Alternatively, “fast” is subjective but “supersonic” is very specific. Here is a bit of a weird one since an object going just above mach 1 might be either “transonic” or “supersonic”; also, what speed of sound are we referring to? The actual definition takes care of this but it’s still somewhat of a non-universal term: if an alien read the definition 1000 years from now, would they be able to properly identify supersonic objects?
However it’s usually pretty obvious. You can’t have the discussion of “what is a chair?” or “what is a man?” with a technical term. If it fits the definition it is within the category. If not, then it’s outside the category.
All of this is to say, when doing technical writing or explanation, be very cognizant of the technical and non-technical terms you are using and want to/should be using. You can even define your own technical terms within your explanation but be sure to really mark what you are defining since English words have so many different meanings and uses.