taXi eXit eXpress train miX siX heXagon boX foX aXe Xerox X-ray X-mas tree Xylophone
These are just a few words that contain the letter X. It is notoriously difficult to name words that begin with the letter X, due to the fact that its' regular "/ks/" sound doesn't appear at the beginning of any* English words. However, words such as "Xylophone" and "Xray" somewhat fufill this roll (Despite not beginning with the sound). X comes from the letter "Chi", which made the "/s/" sound. Often, "Kappa" (which would today become "K") would come before it, to add a "/k/" sound before "/s/". The Kappa would sometimes get dropped, but the sound would stay. This resulted in Chi making both sounds at by itself. Thus, X was born.