For example, this question: What does the term "carebear" mean in Eve Online?, or a hypothetical question about what "gg" means. Do they fall under this site's purview?
Jeff has stated - in the context of other sites - that "there is no such thing as a stupid question". And like they say on "Who Wants To Be A Millionaire" a question's only easy if you know the answer.
Someone who is new to a game won't know the "common" terminology, especially if it's used by everyone else with little or no context. So rather than showing yourself up as a complete noob on the game you need to ask the question somewhere else.
Here would seem a good place.
It depends on the term being discussed. Some definitions are very clear (What is frag in FPS?) but some terms might be considered subjective.
For example I strongly disagree with the second definition of carebear on UrbanDictionary (the one about Eve-Online)