Is 'terse conciseness' redundant?
Solution 1:
Redundant? Almost completely.
These words overlap 90%, and the tiny 10% difference isn't really enough to avoid being redundant, even if a shred of difference is truly present. Redundancy is measured in degree of overlap versus the degree of separation.
Second problem: these words tug their connotations in opposite directions, which muddles the already tortured meaning.
Conclusion: zero style points for using these together. Their incomplete overlap is a technicality. They are redundant enough.
BTW: this is a great family of synonyms relating to bevity of language:
*) Terse is tense and possibly rude. Brief, yes, but not in a good way.
*) Succinct speaks lucidly. Brief, yet clear.
*) Concise contains a lot despite its small size. Brief, yet comprehensive.
*) Laconic is just brief; it doesn't hint at other virtues. Unlike terseness, its connotation is usually neutral, and it alone is useful among this synonym family for describing an individual's personality generally (versus their specific words).
Solution 2:
Is 'terse conciseness' redundant?
Yes, I think so.
Although it probably depends on how finicky you want to be about it. If I had to pick some differences, and at the risk of rephrasing what tralston already stated;
Brevity is surely a subset of both terse and concise, so terse brevity is almost certainly redundant.
With regards to terse conciseness; the two words seem to overlap but don't have identical meanings, so terse conciseness has a different meaning (or at least connotation) to either terse or concise.
Terse means brief and cut short, it has negative connotation as it is usually associated with rudeness.
Concise implies clarity and a sparse use of words to describe something succinctly. It tends to be used to describe positive traits.
I would interpret terse conciseness to mean a form that is short, with meaning conveyed but with a potentially negative demeanour.
Here are some examples to illustrate how I view the differences, in response to "what are you up to?"
- Terse "Stuff! Leave me alone."
- Concise "I am building a play-house and don't want to be distracted"
- Terse Conciseness "I am building a play-house. Leave me alone!"