What is the X in X-mas?
late 14c., from Old French coment "commentary" or directly from Late Latin commentum "comment, interpretation," in classical Latin "invention, fabrication, fiction," neuter past participle of comminisci "to contrive, devise," from com-, intensive prefix (see com-), + base of meminisse "to remember," related to mens (genitive mentis) "mind" (see mind (n.)). The Latin word meaning "something invented" was taken by Isidore and other Christian theologians for "interpretation, annotation." No comment as a stock refusal to answer a journalist's question is first recorded 1950, from Truman's White House press secretary, Charles Ross.
early 15c., from Middle French commenter (15c.), from Latin commentari, from commentum (see comment (n.)). Related: Commented; commenting.