What is the X in X-mas?
early 14c., from Old French panel "piece of cloth, piece, saddle cushion" (Modern French panneau), from Vulgar Latin *pannellus, diminutive of Latin pannus "piece of cloth" (see pane). Anglo-French legalese sense of "piece of parchment (cloth) listing jurors" led by late 14c. to meaning "jury." General sense of "persons called on to advise, judge, discuss," etc. is from 1570s. Sense of "distinct part of surface of a wall, door, etc." is first recorded c.1600.