What does Boxing Day have to do with boxing?
Old English mawan "to mow" (class VII strong verb; past tense meow, past participle mawen), from Proto-Germanic *mæanan (cf. Middle Low German maeyen, Dutch maaien, Old High German maen, German mähen "to mow," Old English mæd "meadow"), from PIE root *me- "to mow, to cut down grass or grain with a sickle or scythe" (cf. poetic Greek amao, Latin metere "to reap, mow, crop," Italian mietere, Old Irish meithleorai "reapers," Welsh medi). Related: Mowed; mown; mowing.
"stack of hay," Old English muga, muwa "a heap, swath of corn, crowd of people," earlier muha, from Proto-Germanic *mugon (cf. Old Norse mugr "a heap," mostr "crowd"), of uncertain origin.