What does Boxing Day have to do with boxing?
late 15c., from Middle French javeline (15c.), fem. diminutive of Old French javelot "a spear," probably from Gaulish (cf. Old Irish gabul "fork;" Welsh gafl "fork," gaflach "feathered spear"), ultimately from PIE *ghabholo- "a fork, branch of a tree." Also found in Italian (giavelotto) and Middle High German (gabilot). Javelot also was borrowed in Middle English, but this is the form of the word that has endured.
(1.) Heb. hanith, a lance, from its flexibility (1 Sam. 18:10, 11; 19:9, 10; 20:33). (2.) Heb. romah, a lance for heavy-armed troops, so called from its piercing (Num. 25:7). (See ARMS.)