Xi (uppercase Ξ, lowercase ξ) is the 14th letter of the Greek alphabet.
Xi There are other meanings outlined on the linked Wikipedia page. I hadn't thought much about it until I began playing
You know that feeling? The search for something ~ anything ~ to use those last two tiles when you're already 30 points behind? I'm glad to learn this is more than just a two-letter word ~ it should be easier to remember but I'm beginning to wish I'd studied something besides Latin.
And that I played e-mail Scrabble with someone less talented than my oldest granddaughter who beats me soundly.