To some Reference is as much a part of having a PDA as PIM functions.

Whipping out a PDA to look up a contact is much the same as pulling one out to look up a dictionary or language translation reference.
MDict by Octopus Studios provides an expandable environment to read a range of precompiled reference titles directly on the Handheld PC including Dictionary, Thesaurus and translation dictionaries.

Read: MDict 2.1