DICT is a file format and protocol for dictionaries and dictionary queries.
To use DICT, you will need - a DICT client installed on your computer - a DICT server, either running on your computer or available on the Internet - one or more DICT dictionaries, if you're running a local server on your computer
Ubuntu (GNOME) comes with a default DICT client, accessible from the Applications menu (Accessories > Dictionary).
Kubuntu's default client is KDict, accessible from the K menu (Internet > Online Dictionary). A "Dictionary" applet for the panel is also available, and can be added to a panel by right-clicking on the panel and selecting "Add applet to panel".
The clients come configured to connect to Internet DICT servers. If you, however, would like to install a server locally, you can install the package dictd or serpento using !!!any method.
You will then have to install one or more dictionaries. Dictionaries for English are provided in the dict-gcide and dict-wn packages, while the package dict-moby-thesaurus offers a thesaurus.
To use your newly installed local DICT server, you will have to configure your client accordingly.