Some bullshit politically correct term to avoid saying the dreaded word "Christmas" even though everyone knows that's exactly what you're fucking talking about.
Anal uptight liberal American: Why, hello little Muslim person, I wish you a happy holiday season on this December 25!
Muslim: Don't you mean 'merry Christmas'? I mean... it's fucking Christmas, for fuck's sake.
Anal uptight liberal American: *head explodes*