A multilingual dictionary will typically consist of one or more bilingual dictionaries (one or both directions) and the prerequisite lookup (ie, retrieval) software. Most lookup packages are designed to accommodate more than one dictionary, although only one dictionary can be active at a time.
The retrieval software is generally designed to work in conjunction with wordprocessing software, although the specific manner in which this is implemented varies, depending on the operating systems.
A still rare but very welcome feature is inflectional morphology in lookup routines; this means that one does not have to enter a root form to retrieve an entry.
Several packages support supplementary and user dictionaries. Ideally, these are integrated in such a way that they are automatically searched at the same time the main dictionary is searched.