X is for Xylophone and Xi, and Xu

Xylophone, the musical instrument made of wooden panels, picture from Wikipedia

"Xylophone" by Roumpf - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons

  Incidentally Wikipedia says that the xylophone may have originated in Asia.

Of course, for this X post, I just had to look up the Scrabble dictionary, for 2 letter words with X and there were just the 2 words--Xi for a letter of the Greek alphabet and Xu, a Vietnamese coin.