petrichor: (PET-ri-kuhr) noun, The pleasant smell that accompanies the first rain after a dry spell.
[From petro- (rock), from Greek petros (stone) + ichor (the fluid that is supposed to flow in the veins of the gods in Greek mythology). Coined by researchers I.J. Bear and R.G. Thomas.]
I love this word because it evokes a the senses – both the smell and the sight of a rainwashed day. Plus it took me a long time to learn to pronounce, and I love a good challenge.