Dictionaries are quite simple data structures used by ContentMine to do text mining in segments that can be created and controlled individually. All the dictionaries in use by ScienceSource pair search terms with Wikidata items.
Property P16 here stores on an annotation the name of the dictionary from which the term found comes. It may not, indeed, suffice to know the term, since terms may be ambiguous, as English phrases, and may possibly occur in two or more dictionaries in use. Currently dictionaries are named as strings.
For dictionary creation, via SPARQL typically, see WikiFactMine documentation.