Are these good questions? - What does "Dungeon" mean in "Dungeons and Dragons", and how did that meaning come about?
It's the title of a possibly topical question, but it literally lacks body. Without seeing it in its full question form, we can't guarantee whether the community will think it's good.
It's certainly on-topic, within our terminology and history-of-gaming tags, but beyond that mere topicality, judgement about quality would have to be determined the usual way, by people voting on it as a real question on the main site.
Sort of? As SSD says, you're missing the body of the question completely so it's hard to judge, but it's on topic for us. I'm also confused about what exactly you're asking for. You might be confused about what you're asking for, since the Dungeon part of the title literally just refers to a Dungeon (it's meant to be evocative), but your other meta questions suggest you're curious about how the language is actually used nowadays and what's with the way people use it and why it came to be that way.
You might want to just ask that straightforwardly: "what's with D&D players using 'dungeon' the way they do to mean all kinds of places they go kill stuff?" or something.