What is the X in X-mas?
1798, originally in natural history, from Latin aberrantem (nominative aberrans), present participle of aberrare "to wander away, go astray" (see aberration).
aberrant ab·er·rant (ā-běr'ənt, āb'ər-)adj.
Deviating from the usual course, as certain ducts, vessels, or nerves.
Deviating from the normal; untrue to type.
Out of place; ectopic.