The Этимологический словарь русского языка app by TTdictionary is an offline dictionary that covers over 20,000 words. It has a user-friendly interface, and the app's features are easily accessible. The app's main features include a quick search with filters, pronunciation of words using TTS (Text-To-Speech), and a flashcard learning function. Additionally, the app offers a favorites list, bookmarks, and history to save viewed words. It also has a backup and restore function from files or Dropbox.

This app allows users to edit and add new words, as well as search for words through speech recognition. Other features include the ability to adjust the text size, change the color of the interface, and switch the app's language direction. Overall, the Этимологический словарь русского языка app is a great tool for anyone who wants to learn the etymology of Russian words, and it is available for free on Android devices.