What does Boxing Day have to do with boxing?
"unwillingness to endure a differing opinion," 1765, from Latin intolerantia "impatience, unendurableness, insufferableness, insolence," from intolerantem (see intolerant). Especially of religious matters through mid-19c. Now-obsolete intolerancy was used in same sense from 1620s.
intolerance in·tol·er·ance (ĭn-tŏl'ər-əns)
Extreme sensitivity or allergy to a drug, food, or other substance.