Are big words necessarily pretentious? I'm generally in the David Foster Wallace camp on this one. Somewhere (likely in a teensy footnote-of-a-footnote) he's written about how it's all about the right word in the right context. And if the word that is most accurate and precise happens to be large, well, there's always the dictionary.
Only today I was rereading something I wrote a couple years ago, and I used the phrase "pedagogical reciprocity." I wanted to talk about how sometimes teachers learn from students. Why the heck didn't I just say that?