I see a lot of questions like:
Is it okay to say settable?
which are impossible to answer well because they lack context. How can we discourage this?
The only way is to close them as "not a real question":
It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form.
Once users see those questions are closed, they should hopefully give more context to their questions.
If you are asking about a way to avoid those questions are even asked, I think there isn't. Maybe rejecting some questions, if they match a defined schema, could help, but as far as I have seen, those filters are not much welcome.
Take as example the filter on Stack Overflow that avoids using problem in the question title; it seems users found a workaround to that, and they now write pr0blem, porblem, or similar words.
This question, which had zero context, and almost literally repeats the title in the body:
Word for something sad and funny at the same time
(nor did these edits improve matters)
https://english.stackexchange.com/posts/55839/revisions
Ironically pointed to this meta post:
Indeed, the bittersweet tragicomedy of questions lacking context.
Usually these questions are asked by users with very low rep. I propose that in cases where the question asker has < 200 rep (or some suitably low number) it should require only three votes by high-rep users to close an obviously stupid question.
Can't we just prompt the user to provide context? On the page where you write your question, it says:
Maybe that should be expanded more. It should tell the questioner what is in it for them. For example, "If you want good answers, then you must provide context."