Language is always changing. New words are created and old words shift their meaning or become obsolete. There are some words that would probably be obsolete by now if they hadn’t had the luck of being included in the language of Christmas tradition.
Traditions are, after all, traditional. They keep the old ways preserved. These words are still with us thanks to the yearly reinforcement of the old ways.
‘Tis and ’twas
English uses a lot of contractions on the ends of words, like those in I’ll, they’ve, can’t and he’s. There was a time where we also used words with the contraction at the beginning, such as ’twere, ’twould, th’art, and n’art. The ones we know today have a Christmas carol (“’Tis the season to be jolly”) and a Christmas poem (“’Twas the night before Christmas”) to thank for their survival.
Happy New Year, Happy Birthday, Happy St. Patrick’s Day, Happy Thanksgiving, Happy Groundhog Day. When we want to express good wishes for festive events, religious or not, we go with “happy.”
Except when it comes to Christmas. Then we don’t want you to be happy, we want you to be merry! Merry is a much older word than happy. It originally meant just pleasant or agreeable — the weather could be merry, or a sound or an idea. Happy came later originally meant fortunate.
In the 1800s, the independent use of “merry” went into decline, but stuck around in set phrases like “Merry Christmas.” People did say “Happy Christmas” during this time, but “Merry Christmas” was the phrase of choice in Dickens and in carols and other things that get repeated over and over every time the holiday rolls around.
Sled is an older word than sleigh, which we borrowed from the Dutch slee in the 1700s. Sleigh was originally spelled “slay,” and people added the spelling complications later, on analogy with weigh and neighbor. Sled is still the far more common word for vehicle of transport by sliding, but sleigh sounds and looks a bit fancier. It might have fallen out of favor entirely if it hadn’t been preserved in the tradition of holiday sleigh rides with sleigh bells.
Wassail goes back to a 13th century expression waes haeil, meaning “be in good health.” The waes part is an old form of the verb “to be,” which only survives in our past tense word “was.” Haeil comes down to us as “whole” or “hale,” as in “hale and hearty.”
But the full expression survives as the single word wassail because of the enshrining of the holiday revelry of drinking to each other’s health, which became going door to door and singing to wish good health, which gave rise to carols like “Here we come a-wassailing.”
Tidings is a very old word in English that comes from a verb meaning “to happen or befall.” It means happenings or news. You never see it in the singular form, and these days, you don’t see it much at all except around Christmas, where there are always “tidings of comfort and joy.”
To “deck the halls” is to cover them with beautiful décor. The words deck and décor are not related, though the verb deck is related to the noun deck, which also goes back to the idea of covering.
Deck was more active as a verb in the olden days when you could deck your hair, or speak of being decked with light or of flowers decking a garden. It survives now in the expression of getting “decked out,” which you can do any time, but you can only directly deck an object when that object is a hall being readied for Christmas.