This software is a dictionary and Wikipedia reader that can be used on different operating systems and can be accessed even without an internet connection.
Keep in mind that Aard Dictionary is under active development and isn't currently considered stable software. Nonetheless, many users find it to be quite usable already. Plus, since it's open source, you have the ability to contribute to its continued improvement.
Version 0.8.0 Dev / 0.7.6: N/A