I discovered an interesting website today called TheatreCrafts. There is a ton of information on subjects related to the theatre, including everything from scenic and lighting and rigging to props and makeup and even stage management. The glossary of technical theatre terms is particulary great – you have the option to search in 4 different ways: word search, browse by letter, random word finder, and category. Really fun and interesting to review.
One warning – this is a website from the UK, so some of the terms are different than those used in the US (for example, what we call Sharkstooth Scrim in the US is called Sharkstooth Gauze in the UK). But, for the most part, the terms are interchangeable, and often the site does reference alternate terms (such as the scrim reference above).