What does Boxing Day have to do with boxing?
epiphysis e·piph·y·sis (ĭ-pĭf'ĭ-sĭs)
n. pl. e·piph·y·ses (-sēz')
The end of a long bone that is originally separated from the main bone by a layer of cartilage but that later becomes united to the main bone through ossification.
See pineal body.