Vocabulary Trainer is an Android app developed by Fiete Wennier. It falls under the category of Education & Reference and is compatible with Android 9.0. The app is free to use and offers an effective way of retaining vocabulary.

The app features a learning card system that helps users memorize words and their meanings. Additionally, the app also sends automatic reminders to ensure that users never forget the vocabulary they have learned. However, it is important to note that the vocabulary needs to be manually entered into the app.

Overall, Vocabulary Trainer is an excellent app for anyone looking to improve their vocabulary and retain it for the long term.