Quizlet.com is a great site for reviewing terms and definitions (can be created in numerous languages as well).
The site provides the standard "flashcard-type" studying (with the ability to star cards that need to be reviewed) as well as fun games (such as all terms scattered and users must match the terms quickly and an asteroid game) for the users to try. It also gives the user the ability to create a test from the group of terms and definitions.
An app is also available own the App store and Google Play store.
If you would like a detailed 6 minute video I created - click here (or see the video embedded below). Unfortunately, the helpful annotations will not appear on a mobile phone. I hope in the future they will be.
If you would like a fast-forwarded version of the same video above - but in 1 minute - click here (or see embedded video below).