Q. gazetteers

There are lots of free online dictionaries that can define terms for you, including gazetteers. We have a nice collection on our Reference page in the Best Free databases: Dictionaries box on the databases page (see link, below). Just pick one, type in gazetteers and you'll have your definition!

I also found a good description in the Maps and Remote Sensing Imagery guide at StonyBrook University, linked below.