Why do we “deck” the halls?

As the holidays approach, I’m sharing a little linguistic trivia related to the traditional Christmas song, “Deck the Halls,” courtesy of Jessica Strasbaugh at Oxford Dictionaries.
You might wonder, when singing this carol, what exactly we are doing to the halls when we deck them with boughs of holly. (I, at least, would as a child confusedly imagine a person punching walls in a hallway, in a more modern sense of the verb: “to knock someone to the ground with a punch”). However,deck in this sense actually means “to decorate or adorn brightly or festively” and comes from Middle Dutch decken “to cover”. The word is related to the noun deck (of a ship, etc.), originally denoting canvas used to make a covering (especially on a ship); deck came to mean the covering itself, later denoting a solid surface serving as roof and floor.
The second verse of this famous Christmas carol also has some neat etymological background that you might not think of when singing it:
Don we now our gay apparel
Fa la la la la, la la la la
Troll the ancient Yuletide carol
Fa la la la la, la la la laDon, the verb meaning “to put on clothing”, is actually a contraction of ‘do on’ with the same meaning (from Song of Solomon in the Coverdale Bible “I haue put off my cote, how can I do it on agayne?”). The other odd verb in this verse—troll—means “to sing something in a happy and carefree way” and comes from late Middle English, in the sense ‘stroll’ or ‘roll’. Interestingly, the verb troll has a relatively new meaning related to the Internet: “to make a deliberately offensive or provocative online posting”. But this verb (in either sense) is not, in fact, related to the frightening mythical creature most would know this word by! (Though it’s easy to imagine that people who troll in this newer sense would look like one.)
Yuletide, as you probably know, is an archaic word for “Christmas” or “Christmastime”. The word Yule comes from the Old English gēol(a) for “Christmas Day”, and may be compared with Old Norse jól, originally applied to a heathen festival lasting twelve days, and later to Christmas. Tide, on the other hand, has origins in the Old English tīd, “time, period, era” (and is related to Dutch tijd and German Zeit, as well as ultimately to the word time). We tend to know tide, however, as the rising or falling of the sea; both senses are etymologically related (indeed, the ocean’s tide is closely bound with both ancient and current conceptions of time). However, the marine sense first dates to later Middle English.
If, like me, you’re entertained by this sort of thing, you can read more from Jessica about the vocabulary of other Christmas songs.
I’ve always assumed “deck” was just an old form of “decorate”. Thanks for the detective work and Merry Christmas!