What does Boxing Day have to do with boxing?
mid-15c., variant of tapissery (early 15c.), from Middle French tapisserie "tapestry" (14c.), from tapisser "to cover with heavy fabric," from tapis "heavy fabric," from Old French tapiz (12c.), from Vulgar Latin *tappetium, from Byzantine Greek tapetion, from classical Greek, diminutive of tapes (genitive tapetos) "tapestry, heavy fabric," probably from an Iranian source (cf. Persian taftan, tabidan "to turn, twist"). The figurative use is first recorded 1580s.