A free program for Android, by DocCheck.

DocCheck Flexikon – The Community for Healthcare is one of the largest and most popular communities for medical and health. You can find here an extensive collection of medical definitions and other important medical information. The content of the app is organized in an easy and convenient way, so you can find what you need in seconds. The app is designed to help you improve your knowledge of medical terminology.

This is a free app, and you do not need to register to use it. You can find all the information in the simplest way, without any registration or sign-up.