The twenty-fourth letter in the alphabet, which derived from the North Semitic letter taw, although taw primarily represented the "T" sound. In Greek, it became the letter chi, possessing the same form as the modern "X," and represented a "kh" sound (as in the Scottish loch). It eventually passed into Latin, where it became used to represent the "ks" sound. Interestingly, the Greek letter chi (or "X") was used in the Middle Ages to represent the name "Christ." As a result, we have the modern word "Xmas" to refer to "Christmas." Although some people find the word "Xmas" to be the height of modern, late-twentieth-century tackiness, it actually isn't, and has a long historical tradition.