Just use the word "Excessmas" for the secular celebration that takes place in December and "Nativity" for the celebration of Jesus Christ's birth. Your office party is probably an "Excessmas" party but you go to a "Nativity" candlelight service at a church on Christmas Eve.
Well, not the Oxford English Dictionary, but check this out from
Addictionary :
DEFINITION:(noun) The act, in a material sense, of overdoing the Christmas Holiday. Excessive spending in hopes of getting that "special holiday feeling". Too much decoration. Too many disposible gifts. Alternate use: too much celebration with food and/or adult beverages.
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