Ornaments.
holly
the word that starts with the letter o isonizalation glad to help
Advent.
Xmas
Elves.
Another word for water that starts with the letter 'O' is oxygen dihydrogen.
There are a couple of Christmas songs with the word "wreath" in it. These are O Christmas Tree and Christmas Is All In The Heart.
A few things that start with o and have to do with the winter are oreos to put out for Santa. That's one thing that starts with an o and it has to do with winter but mostly Christmas.
yuletide carol
o my god
Lions can be described as overpowering. The word starts with the letter o.