I just came across a rather nice dictionary of wargaming hobby terms on the blog Wargaming Tradecraft - a gamers' grimoire if you will! It would be very useful for those new to the hobby and there's plenty there for the more experienced hobbyist to explore.

Here's the link: Wargaming Tradecraft: Wargaming Hobby Dictionary: Below is an alphabetical list of various terms you'll come across while hobbying, brief descriptions of them and links to articles ...