What is the X in X-mas?
c.1300, "horse trained for chasing," agent noun from chase (v.), probably in some cases from Old French chaceor "huntsman, hunter." Meaning "water or mild beverage taken after a strong drink" is 1897, U.S. colloquial. French had chasse (from chasser "to chase") "a drink of liquor taken (or said to be taken) to kill the aftertaste of coffee or tobacco," used in English from c.1800.
a literary work or portion of a literary work that is of a light or mollifying nature in comparison with that which precedes or accompanies it. The metaphor may stem from the practice of following the consumption of strong alcoholic drink with consumption of a less-potent beverage or, occasionally, with food.