Again, the internet is a great resource on many topics. While it is advisable to consult your accountant with your tax questions, from time to time you might want to understand some tax terminology yourself. There are several Tax Glossaries on the internet. Here are a few that I found.
http://taxes.yahoo.com/glossary/
http://www.totaltaxsolutions.com/glossary.htm
http://www.firstcommand.com/home/tax_command/tax_glossary/index.html
http://www.cyberhaven.com/taxlibrary/taxglossary.html
There were several others that were ASP, PHP, or JSP driven, so I did not include them.