I found this website a few years ago, and I love it. It's free!! Easy to use--you can create a list of words or terms yo need to know, such as science or math terms (theorems?), vocabulary, etc., as well as their definitions (or answers) and save it. Then you can use the site to create flash cards, play study games, or quiz yourself in whatever format you like (there are multiple choice, matching, etc.).
I will generate vocabulary or terminology quizzes using this website, and I've had many students in the past say that it was a really helpful tool.