The HarperCollins Dictionary of Mathematics

Rating:
Summary: This is the Math Dictionary you want.
Review: There are a number of mathematical dictionaries, of course. This effort is widely comprehensive (it would be a challenge to discover a topic not included) and sufficiently treats each topic. Masters level in coverage, it is accessible for undergraduates. I find it invaluable as a quick reference.

Rating:
Summary: Fabulous repository of mathematical terms
Review: This is the best dictionary I have ever seen for undergraduated. This dictionary is complete, clear and not expansive. It is not complete as a CRC encyclopedia for graduated but for an undergraduated and even a beginning graduate it is the best one, because it explains all terms you can encounterand many more. Also it has biographies of great mathematicians. If you look for a dictionary of mathematics buy this one.