You can use truncation to find variations of a single term. In Gerritsen Online, use a ? at the end of your term to match all terms with a single additional letter or number, and use a * at the end of your term to match all terms with more than one letter or number.
For example, literat? will retrieve results containing ''literate'' and ''literati'', but not''literature'', while literat* will retrieve results containing ''literate'', ''literati'' and ''literature''.