I took a course on English writing as a requirement for my Industrial Engineering undergraduate degree at the University of Toronto (the other U of T). The only thing I remember from that class is that I'm supposed to avoid using redundant words, e.g., "dead corpse" and "end result". I just learned today that these redundancies are called pleonasms.
The opposite of a pleonasm, is an oxymoron (the plural of which is "oxymora", not "oxymorons"). Here's a list of some quotes containing oxymora. I'll provide one below that is especially meaningful to me lately because I just watched the movie "Matrix Reloaded":
We must believe in free will. We have no choice. -- Isaac B. Singer
I first read about this in the MetaFilter Weblog.