There are many different ways to wish someone a merry Christmas in different languages. Here are a few examples:
In Spanish, you can say "Feliz Navidad".
In French, you can say "Joyeux Noel".
In German, you can say "Frohe Weihnachten".
In Italian, you can say "Buon Natale".
In Portuguese, you can say "Feliz Natal".
In Russian, you can say "S Novym Godom".
In Japanese, you can say "Merry Christmas" or "Merii Kurisumasu".
In Chinese, you