good question, we don't have a glossary of terms currently, but we do have a pic of the many tools that photoshop comes with posted in the tutorials section.
http://lucidgfx.ipbfree.com/index.php?showtopic=19if you're curious about certain terms you can ask me and ill do my best to answer your question.
Some common terms you'll hear tossed around here
http://lucidgfx.ipbfree.com/index.php?showtopic=181in additon to these terms you'll probably hear about
LR-Learning Rights-these files are used to help you learn and must be used in that way only.
WR-Wearing Rights-you can put the tag in your sig, but you must give credit to the maker.
FR-Free Rights-you can do whatever you want with it.
As far as photoshop terms, there's so many it's hard for me to go into depth without some direction from you so give me a reply back and ill be happy to answer anymore questions.
http://www.photoshopgurus.com/tutorials/t001.html also, check this guy out. he's great and he's got excellent beginner tutorials.