OmniDictionary is a DICT client by The Omni Group. Unlike Apple Computer's Dictionary, it retrieves definitions from the internet via the DICT protocol instead of a file on the hard drive. Starting with the release of version 2.0.4 is now a universal binary.
Apple have their own dictionary. 
( z1 have :ARG0 ( z2 company :name ( z3 name :op "Apple" ) ) :ARG1 ( z4 dictionary :poss z2 ) )