1021: x-mas Sep 25, 2017

People use plenty of abbreviations, initialisms, and acronyms, but almost always these will take the beginning letter or letters of a word, without changing them. 'Christmas' however is often, informally written as 'x-mas' which neither sounds much like nor is spelt as the beginning of the original word. Instead, the X represents the Greek letter chi, which in lower case looks like χ. This letter actually does act as the initial, but it comes from the Greek word 'χρῑστός' ('Khristos') meaning ‘Christ’. There are indeed a lot English words for Christian terms, often coming from the Septuagint.