What does Boxing Day have to do with boxing?
c.1200, covent, cuvent, from Anglo-French covent, from Old French convent, from Latin conventus "assembly," used in Medieval Latin for "religious house," originally past participle of convenire "come together" (see convene). Not exclusively feminine until 18c. The form with restored Latin -n- emerged early 15c. The Middle English form remains in London's Covent Garden district (notorious late 18c. for brothels), so called because it had been the garden of a defunct monastery.
COVENT GARDEN ABBESS. A bawd.
COVENT GARDEN AGUE. The venereal diſeaſe.
["Classical Dictionary of the Vulgar Tongue," 1796]