What does Boxing Day have to do with boxing?
late 14c., from Old French contumelie, from Latin contumelia "a reproach, insult," probably related to contumax "haughty, stubborn," from com-, intensive prefix (see com-), + tumere "to swell up" (see thigh).
The unhappy man left his country forever. The howl of contumely followed him across the sea, up the Rhine, over the Alps; it gradually waxed fainter; it died away; those who had raised it began to ask each other, what, after all, was the matter about which they had been so clamorous, and wished to invite back the criminal whom they had just chased from them. [Thomas Babington Macaulay, "Lord Byron," 1877]