What does Boxing Day have to do with boxing?
"of or belonging to an apex," 1828, from Latin apicem, from apex (see apex) + -al (1).
apical a·pi·cal (ā'pĭ-kəl, āp'ĭ-)adj.
Relating to the apex of a pyramidal or pointed structure.
Situated nearer to the apex of a structure in relation to a specific reference point.