There's a site called OneLook where you can put in a definition and it tells you the word. Well, I didn't believe this claim at all (there's a pseudo-apocryphal urban myth about a computerised translation system that rendered out of sight, out of mind as blind mad) so I decided to test it by trying the definitions of some of my favourite words. I put in area between nose and lips, dark rusty colour, relating to breakfast and beautiful buttocks and it came straight back with philtrum, fuscoferuginous, jentacular and callipygian.
Then, because I like to put a pretty picture at the bottom of each post, I put all four words into Google to see if there were a picture that combined them all. Nothing! I'm not sure what the picture would have looked like, but I'd like to have seen it nonetheless.
Instead, I'll tell you that there was a cult in classical Syracause dedicated to Aphrodite Kallipygos, or Venus of the Beautiful Bottom. At least, there may have been. All we know about it comes from an ancient Greek chap called Alciphron, who spent his time composing imaginary letters.
The Greeks carved statues of the goddess making her as callipygian as they possibly could. It was far too much for one young man, but to find out about him you'll have to follow this link to Lucian's Venus of Knidos and read paragraphs fifteen and sixteen. I promise you that it's terribly, terribly funny.
An immodest deity
P.S. For the latter half of this post I was using my copy of Nigel Spivey's Understanding Greek Sculpture, which is awfully good.
P.P.S. I knew about callipygian before, though, as it pops up in Aldous Huxley's Antic Hay, which is probably my favourite novel.