An idiomatic verb for a question that is still open and unanswered?

Question

There is a vast literature on this topic but this important question/problem is still _____ .

Among the questions/problems that are yet ______ in this field is about the relation between X and Y.

I am looking for a verb to say that there is no answer at all for that question, or that there is no noticeable answer or approaches to answer it, or that the question is still quite open.

I can simply say unanswered but that seems a bit too determined. I also thought of open and then I came to unsettled which seems to me the most idiomatic option in that context. What do you think? Any other suggestions?

Answer 1

The Google search results within site:gov:

• question "unresolved" = 456.000 results
• question "unanswered" = 205.000 results

In scientific texts, it's common to say that a question is still unresolved, but unanswered is also common and sounds completely normal to me - and I search through these texts a lot.

If you further narrow down the search to PubMed, a large online library of medical documents (site:ncbi.nlm.nih.gov/pubmed), you can see that unanswered and unresolved are used much more often than unsettled - many non-native English speakers might have a problem to understand this term.

You can also say that the question is still open, but in certain contexts this can mean that "the question is still open to debate," in the sense like the shop is open till 9 p.m.

You can also reword the sentence and say the evidence about this and this is lacking, insufficient, unconvincing, unconclusive, conflicting, weak, moderate...This gives you more options to say exactly what you want.

Answer 2

I think you can use the verb "unsolved".this important problem is still unsolved. Or you can say answer to this problem is still unknown.