What does Boxing Day have to do with boxing?
c.1300, "store, treasure," from Old French garison "defense" (Modern French guérison "cure, recovery, healing") from garir "defend" (see garret). Meaning "fortified stronghold" is from early 15c.; that of "body of troops in a fortress" is from mid-15c., a sense taken over from Middle English garnison "body of armed men" (late 14c.), from Old French garnison "provision, munitions," from garnir "to furnish, provide."
1560s, from garrison (n.). Related: Garrisoned; garrisoning.
(1.) Heb. matstsab, a station; a place where one stands (1 Sam. 14:12); a military or fortified post (1 Sam. 13:23; 14:1, 4, 6, etc.). (2.) Heb. netsib, a prefect, superintendent; hence a military post (1 Sam. 10:5; 13:3, 4; 2 Sam. 8:6). This word has also been explained to denote a pillar set up to mark the Philistine conquest, or an officer appointed to collect taxes; but the idea of a military post seems to be the correct one. (3.) Heb. matstsebah, properly a monumental column; improperly rendered pl. "garrisons" in Ezek. 26:11; correctly in Revised Version "pillars," marg. "obelisks," probably an idolatrous image.