Russell,
Frankly, memorization of what "WBS" or "Work Breakdown Structure" means is absolutely NOT important.
But... knowing how, when and why to use a WBS, and what its importance in scope management and the success of your project means, is indeed important.
So it is indeed a good idea to read through the glossary, and if you come across a term that is unfamiliar you should not just memorize the term, but instead, learn about how to use it on a project. Or potentially even begin using it on your own projects.
