What does Boxing Day have to do with boxing?
late 15c., "to use to one's profit, to increase (income)," from Anglo-French emprouwer "to turn to profit" (late 13c.), from Old French en-, causative prefix, + prou "profit," from Latin prode "advantageous" (see proud). Spelling with -v- was rare before 17c. Meaning "to raise to a better quality or condition" first recorded 1610s. Phrase improve the occasion retains the etymological sense. Meaning "to turn land to profit" (by clearing it, erecting buildings, etc.) was in Anglo-French (13c.) and was retained in the American colonies.