Recently I studied some cognitive psychology and it gave me a lot of new interesting insights and terminology that I can use in game design. I had a similar revelation when studying graphical design many years ago. I don't plan a career in game production, but I would still like to increase my knowledge in game-design vocabulary & terminology.

Those of you who have a more formal education and/or working in the industry; do you have any suggestions of good books or other sources for terminology?

Reading some random tutorials works, but I would like something more concise authoritative(?), e.g. something that can be considered a standard.

This is a very good question, but unfortunately I don't think there is a good answer to this. The study of game design is something relatively new, and because of this many of the terms used are non-standardized. There are online resources such as the video game section of TV Tropes which has a vast, community-built list of such terms, but this is obviously non-standardized. You also have resources such as Extra Credits which go into much detail about certain terms, but again it's not standardized. Even within school courses on game design I'm sure you'll find terminology varies greatly between different schools.

With that being said, far more important than knowing the terminology is understanding the meaning behind each term. It isn't enough to read a list of terms, you need to be able to identify them as you are analyzing a game.

It isn't enough to read a list of terms, you need to be able to identify them as you are analyzing a game.

You are quite right about this. It can very easily happen that you fall into the pseudointellectual trap and look like a fool

I've never really thought about understanding game design solely through accepted terminology.

The benefit of having terms and definitions that are a bit clearer in definition is that you can communicate better and you will have less misunderstandings. The experience of a game is quite abstract and based on feel, but in order to improve games and give commentary you need to put words on those feelings. Also, I know for sure that there is a "working language" among game developers, educators and gamers. Simply because every domain that takes itself seriously has this. In the domain of games I think it's usually built around features of the games in combination to technical lingo, which sometimes could make it hard to transfer experience from one project to another. But this is just guessing...