The California Energy Commission's Web site contains a great resource entitled the Glossary of Energy Terms. If you're interested in energy topics or happen to come across an unfamiliar term, this tool will be of great use. Simply choose the letter of the term and hope that it's included -- for example, DAYLIGHTING, which is defined as "The use of sunlight to supplement or replace electric lighting." If you quickly get through the hundreds of terms within the dictionary, the main page offers a link to another similar page called the Electric Power Industry Glossary.