Magical Jelly Bean Portable Dictionary: MJB offers a free, open-source dictionary application that’s both portable and lightweight. Designed to run from a USB device, this portable dictionary allows users to access word definitions on the go.
Lingoes Portable is both a free portable dictionary and portable text translation software. It features a complete dictionary and can translate text and pronunciation of words in over eighty different languages.
Yadabyte Dictionary is an open source, free portable dictionary that is very fast, efficient and most importantly, super easy to use. Like other Yadabyte products, it features only the navigation features you need without the clutter.