One proper name is the town of Bethlehem. One word not directly related to Christmas would be "messianic".
Chemistry is a nine letter word that can be made from the letters in Merry Christmas.
charts
chairs
starch
charms
stairs
starts
christ
carts
tidings
Holiday
chrisms
Pudding
popcorn
The word Mollusk is a 7 letter word.
There are 9 phonemes in the word "Christmas."
The 7 letter word is "Capsule"
7 wishes for 7th birthday
Ability is a 7 letter word.
A 7-letter word for barely boiled is "poached".
pontoon
Can't get a 7 letter word with only 6 letters. The 6 letter word is DESIST.