There are several types of dictionaries : dictionaries which explain words and how they are used , dictionaries which translate words from one language to another , dictionaries that can define multiple words at one time , dictionaries of biography which tell about famous people , technical dictionaries which explain the meanings of technical words or words connected to a particular subject ( sometimes called a thesaurus ) . Dictionaries are most commonly found in the form of a book , but some newer dictionaries , like StarDict and the New Oxford American Dictionary are dictionary software running on PDAs or computers . There are also many online dictionaries accessible via the Internet .