When is my son's first birthday?
[Clue: he was born three weeks ago, on 23 September 2014.]
Originally, as I understand it, the word birthday meant the day of one's birth. It was a one-off event.
I don't want to quarrel with the idea of extending this to cover anniversaries of one's birth. I'm comfortable saying that I've had forty birthdays, or thereabouts.
I'm not sure how far back the concept of celebrating the anniversary of one's birth goes, but it at least pre-dates Moses (Genesis 40:20), and therefore long pre-dates the English word birthday. This isn't a question about how that custom arose, but about the way we use the English word birthday and whether it makes sense. Does it refer to the day of one's birth, or an anniversary, or both?
Convention seems to dictate that my son's first birthday is when he's a year old; his second birthday will be when he's made it through another year; and so on. Now this is odd: if his first birthday is in a year's time, what's become of the day of his birth? Is this now considered not to be a birthday at all? I'd have expected him to become a year old on his second birthday, and so on.
In summary, the language drift seems to have gone like this:
- notion of birthday = the day of one's birth;
- notion of birthday extended to include anniversaries;
- notion of birthday now restricted to exclude the day of one's birth.
Is this a bit weird, or what? Has it just happened so that the cardinals (four years old) line up with the ordinals (fourth birthday)?
Is it because birthday is now shorthand for anniversary of one's birth?
Am I missing something?
I can't speak to the history of the usage, but basically, yes, "birthday" means the anniversary of your birth, not the original day of the event. People rarely refer to the day someone was born as his "birthday". Rather, we call that "the day he was born". If you want to know the date someone was born, including the year, you don't ask, "When was your birthday?", you ask, "When were you born?" If you asked someone, "When was your birthday?", they would be much more likely to answer "Last Thursday" or "That was way back in March" than "1963". When someone who is designing a form wants to know the day and year you were born, they don't label the space "Birthday", they label it "Date of birth".
Given that, it makes sense to call the day one year after a person was born his "first birthday", a year later is his "second birthday", etc. Just like we say that one year after you are married is your "first anniversary", etc.
As I say, I don't know the history. I don't know if English speakers ever called the day that someone was born his "birthday". Whether it started out that way and the meaning has shifted, or whether "birthday" has always meant the anniversary of one's birth, I don't know. According to http://etymonline.com/index.php?allowed_in_frame=0&search=birthday&searchmode=none, we get the word from an Old English word that referred to an anniversary, not the original event. So maybe that means it was always an anniversary.
Your son's first birthday will be 23 September 2015.
23 September 2014 was his zeroth birthday. Like C arrays, laws of thermodynamics, and the days of March, birthdays are zero-indexed.
I stumbled upon that some time ago while coding, after all naming convention is very important to proper software architecture :) My conclusion was, birthday = anniversary, birthdate = date of birth.
You can understand this if you are familiar with the concept of abstraction - what is a day if not a date without a year (Independence Day, Labour Day, etc)? and what is a date if not a day with an explicit year? (Independence Day 1975, Labour Day 1975, etc)
So:
A date specifies a day for a specific year
A day specifies a date independent of year
Example:
Birthdate = 22/06/1962
Birthday = 22/06
It makes sense to use birthdate for the day your son was born and birthday for that day in whichever year - which coincide with the celebrations (including the birthdate).
Very nice question :)
There is no reason to think that birthday is shortened from anything. There are several phrases with day which mean "anniversary" or "commemoration" - name day, saint's day, Independence Day. Birth day (as a phrase) fits in to this pattern.
The first meaning given for birthday in the OED is "the day on which anyone is born" (with transferred and figurative meanings), and it is not marked as obsolete. But the latest example given is from 1858.
The second meaning is the familiar one of "The anniversary or annual observance of the day of birth of any one", with the first example around the year 1000, and the first securely dated example from 1382.
So in answer to the question, I don't think there's anything odd about the numbering: the usual meaning of word is the anniversary.