I will leave two comments below for simple yes/no votes.
To document what happened:
A tag terminology was created.
The old tag terminology-and-notation was split and does not exist anymore.
The above was discussed before.
In the process also noted the new tag language-use and thought it is now superseeded by terminology and I thus removed it. If you would like to keept it feel free to recreate it (it was just on the one question).
I feel that terminology (the names we give objects) and notation (the symbols we use to describe objects) are different things and should have different tags. That is, I propose we remove the tag terminology-and-notation and add a tag terminology.
I agree with the examples given by Brendan Sullivan in the comments.
I was going to respond to quid's comment below by saying:
"Right now there are only a few questions on the site and so it would make sense to have just one tag for both concepts, but in the future when there are more questions, it might make more sense to have two separate tags to allow more specific searches. Starting with two tags now would eliminate the future problem of trying to re-tag the older questions."
But I realized that I was thinking in "mathematician" mode and not in "mathematics educator" mode. If the use of terminology in education and the use of notation in education are similar, then I would have no problems with using just one tag terminology-and-notation for both concepts.
The current situation seems unfortunate and I think some change should be made. At the moment there seems no clear consensus yet, but there is also one aspect that was not yet brought up.
I will try to summarize the situation as I see it and propose several solutions.
This situation feels strange as the latter is a subset of the former and the situation is asymmetric in that there is no tag terminology (except there is one in some sense, see below)
Keep only terminology-and-notation
One could envision still other things but these seem the two options. I have a slight personal preference for the former (which seems to be shared by some), but there are also some that would prefer to keep the tags separate and when in doubt I think we should rather keep (meaningful) tags. Thus, I propose to go for 2.
There is an additional issue, namely there is a tag terminology-of-education it has only two questions at the moment. It was introduced for a question asking about some terminology in mathematics education (as opposed to mathematics itself), yet then the second questions seems to use it for mathematics terminology.
It is not clear to me how to proceed. Assuming we go for 2. above, the two main options seem:
We could only have terminology for all questions of terminology.
We could have terminology for mathematical terminology and keep terminology-of-education for education terminology. (Perhaps the terminology should then be also decorated with mathematics in some way?)
What are opinions on this? (Mine is as often rather for fewer tags, so 1.)