Offline dictionaries is an app that lets you look up any word in the dictionary without needing an active Internet connection. Obviously, you do need Internet for downloading the dictionary itself, but after that you can use it as many times as you want without it. By default, the dictionaries are downloaded to your Android's SD card, and if you don't have one, they go onto your device's memory as usual.
The app is especially useful for those planning a trip to a foreign country. With it you can have a handy dictionary while offline, which might often be the case when you're abroad.
Offline dictionaries is a pretty good dictionary app. Its interface is not particularly nice or pretty, but it still works perfectly well.