What does Boxing Day have to do with boxing?
early 15c. (implied in adapted) "to fit (something, for some purpose)," from Middle French adapter (14c.), from Latin adaptare "adjust," from ad- "to" (see ad-) + aptare "join," from aptus "fitted" (see apt). Meaning "to undergo modification so as to fit new circumstances" (intransitive) is from 1956. Related: Adapting.