We call this morpheme processing, and it is generally smarter than
a traditional "stemming" algorithm. It doesn't just rip the end off a word,
it actually checks to see if it could be a valid form of the search term.
More information is available at http://docs.thunderstone.com/site/texisman/link_ling.html .
Notes: Thesaurus terms are also treated in the same manner.
Words smaller than 4-5 characters will not be morpheme processed.