yes
The word birthday need not be capitalized, but if someone's birthday is, for example, February 6th then the month is capitalized. Birthday should be capitalized when it is the first word in a sentence. It will also be capitalized if it is a proper noun. An example would be if someone's name was Birthday Jones, that would be capitalized.
Technically, yes. Unless he's getting a bathroom for his birthday ("a birthday john"). But this is seldom important in informal writing such as cards and congratulatory messages.
Yes birthday is a compound word. The words are birth and day.
It means: birthday. This is the word in Spanish for the English word: birthday.
Yes, the word 'birthday' is a noun, a word for the day or the anniversary of a person's birth; a word for anniversary of something beginning; a word for a thing.
Word processing
Yes birthday is a compound word. The words are birth and day.
יום הולדת is birthday in Hebrew.
Birthday in Swedish is the same as "Födelsedag"
There Is three Syllables in birthday
Yes, but in this case it's not a plural use. It's a possessive. You need to add an apostrophe to show ownership of the birthday. It's Kim's birthday, the birthday of Kim. Just write: In honor of Kim's birthday. The word Kim's is not plural here, but it is correct with the possessive.
To make an acrostic poem from the word birthday you would take each letter in birthday and have the first word of each verse or line start with that letter.