box (n.1.) Look up box at Dictionary.com
O.E. "a wooden container," also "type of shrub," from L.L. buxis, from Gk. pyxis "boxwood box," from pyxos "box tree," of uncertain origin. Slang meaning "vulva" is attested 17c., according to "Dictionary of American Slang;" modern use seems to date from c.WWII, perhaps originally Australian, and on notion of "box of tricks." Boxy is attested from 1861. Box office is 1786; in the fig. sense of "financial element of a performance" it is first recorded 1904. Boxing-day (1849) "first weekday after Christmas," on which postmen and others expect to receive a Christmas present, originally in ref. to the custom of distributing the contents of the Christmas box, which was placed in the church for charity collections.
box (n.2.) Look up box at Dictionary.com
"a blow," c.1300, of uncertain origin, possibly related to M.Du. boke, M.H.G. buc and Dan. bask, all meaning "a blow," perhaps imitative. The verb meaning "to fight with the fists" is from 1567. Boxing as a sport is first recorded 1711.