My very favorite word is Windowsill. It just sounds so pretty when you say it. Go ahead, try it out loud. "Windowsill." See?
Do you have a favorite word?
Another word that I think is really, really pretty is Diarrhea. I'm serious! I don't like Diarrhea the noun, obviously. But if it didn't mean, well, diarrhea it would be a really beautiful word. And I'd probably name my kid that (Only, with one "r"). But I won't. Because it is a noun. And I'm pretty sure that child would hate my for life. That is, if she survived middle school.
And really, who could blame her?