Answer: mcm

AnswerCrossword Clue
MCML x XXXVIII
MCMYear the Paris Metro opened
MCMMcKinley reelection year
MCMOvid's 1,900
MCMLast year of the XIXth century
MCMYear "Tosca" premiered
MCMYear "The Wonderful Wizard of Oz" came out
MCMYear McKinley was elected to a second term
MCMYear of the first Davis Cup matches
MCM1900, on a cornerstone
MCMA year in McKinley's Presidency
MCMNext to last year of Victoria's reign.
MCM1900.
MCMLXXVI x XXV
MCM380% of D
MCMTurn of a century
MCMParis Olympics year
MCMWhen the Boxers rebelled
MCMIt wasn't a CCCLXVI-day year
MCM1,900, to Nero
MCMCI years ago
MCMCXVI years ago
MCMYear McKinley was reelected
MCMCentury-ending year
MCMYear of the Paris Olympic Games
MCMEnd of the 19th century
MCMTurn-of-the-century year
MCMCIX years ago
MCM1900
MCMYear in Leo XIII's reign