Metamorph draws upon a large interconnected web of root words and their equivalence sets called the Equivalence File. For every English word entered as a search item, a lookup is done in this file, and whatever list of associations exists therein is included with the specified root word.
The entered keyword is called the "root". The associations pulled from the Equivalence File are called the equivalences, or "equivs".
Each list of words created from such Equivalence File lookup is passed to PPM (the Parallel Pattern Matcher) for text searching. Morpheme processing is done on all equivalences of all root words. Therefore, all valid word forms of all words in a concept set are searched for.
There are over 250,000 of these word associations contained in the Equivalence File, making a Metamorph search fairly intelligent without the need for customization before trying it.
While the Equivalence File is similar to a thesaurus, it is more accurately comprised of associations of different types, signalling paths of equivalent weightings through a volume of vocabulary.
Where special nomenclature, slang, acronyms, or technical terminology is in abundance, one can customize the Equivalence File by making a User Equivalence File, through which tailored priorities can be ordered and new entries added.