The first owner of the lines names is some like X.... and that is where the X comes from but apologies can't remember the gentlemans surname.
Its me again now rembered where I say the info it is in the Berlitz Complete Guide to Cruising page 255. 'X' is the Greek letter for 'C' and the original owner was Chandris before Royal Caribbean bought is over and kept the 'X' maybe they thought it was for eXcellent.
Thanks for that - what a story, I bought a copy of the book that you have mentioned (little did I know that most of it is on this website!!) but anyway so interesting, so many of the curise companies name the ships after their family. I did not release what a close industry this was - do you think resorts would name after their families.