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[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:

  1. notion of birthday = the day of one's birth;
  2. notion of birthday extended to include anniversaries;
  3. 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?

chiastic-security
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7 Answers7

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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.

user26486
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Jay
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    +1 - So prevalent that in many documents, birthdate is marked as date of birth, shortened to D.O.B. When questioned (in an official capacity, the question is simply, "Date of birth?" No doubt because if asked "Birthday?" people just say "January 1st" (or whatever). – anongoodnurse Oct 06 '14 at 15:02
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    -1 - A lot of forms do use birthday as a way to refer to the original event. (The first two I checked did at least: Facebook and Google, both companies I believe would not risk any confusion). Not to say that in normal usage birthday doesn't function the way you describe, but that's just half the story. – David Mulder Oct 06 '14 at 15:18
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    The common sense method to on forms that use birthday is to check whether there is a field for year or not. If they ask for a year, they're obviously looking for your date of birth (since an anniversary occurs every year). With no other context, birthday to me is the anniversary, not the original. – Gob Ties Oct 06 '14 at 15:28
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    BTW If you used "birthday" to mean the original event, it's not clear what a "second birthday" would mean. Unless you believe in re-incarnation. Well, I suppose there is John 3:4. – Jay Oct 06 '14 at 16:25
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    Isn't there a joke to that effect as well? Something like: Q: "What is your birthday?" A: "June 6" Q: "What year?" A: "Every year." – GalacticCowboy Oct 06 '14 at 17:10
  • @Geobits: That fact however is still that the other meaning of birthday is commonly accepted, I was not saying that "first birthday" doesn't refer to "date of birth + 1 year", only that medica's comment was off and that the answered missed detail. – David Mulder Oct 06 '14 at 21:59
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    @GalacticCowboy this is a joke used in the film Hot Fuzz: https://www.youtube.com/watch?v=yMaiKjsAhIM – Tom Bowen Oct 07 '14 at 15:22
  • @DavidMulder: is your problem only that he did not specify that it can mean both ? – BlueTrin Oct 07 '14 at 16:14
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    @BlueTrin: My problem is with this line '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".' . Although possibly true in a lot of cases, definitly not true in a significant number of cases. – David Mulder Oct 07 '14 at 16:22
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    @DavidMulder Well, now I'll have to start studying every form I see. I wouldn't say that no one, ever, in the history of the world, has labeled a space on a form "Birthday" and expected to get the month, day, and year of the person's birth. But from my anecdotal experience, it's very rare. Now I'll have to do a statistical study. I wonder if I can get a government grant. – Jay Oct 07 '14 at 21:45
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    @Jay: Sorry, but I choose two of the most popular and most used forms including a birthday field in the entire world... actually I can't even think of any form that's more used with a birthday field (Google+ has around a billion registered (not active) users (Google should have more, just can't find any info) and Facebook 1.15 billion registered users (from 2013)... true, not all where filled in in English, but still... that's not - I quote - "no one, ever, in the history of the world") – David Mulder Oct 07 '14 at 21:56
  • @DavidMulder Umm, I said that I WOULDN'T say never in the history of the world. "Wouldn't" = "would NOT". – Jay Oct 07 '14 at 22:02
  • @Jay... I know... but the most popular forms in the world is a LOT (in caps indeed) more than the negative of no one... (though I think the negatives in my comment can be interpreted ambiguously... the fun of Germanic negatives '-_-) – David Mulder Oct 07 '14 at 22:24
  • People rarely refer to the day someone was born as his "birthday" "When is your birthday" is common, but generally refers to the month/day - not specific to the specific year. – Qix - MONICA WAS MISTREATED Oct 08 '14 at 01:41
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    @DavidMulder The problem with those two examples are that they are muddled with UI/UX considerations. To whit: you are not just presented with "Birthday:" and a blank, you are presented with three fields, for day, month, and year, making the implied request for DOB clearer; and yet, year is optional. They don't expect to get DOB there, they expect to get either birthday or DOB, and they'll accept either. They are overloading the meaning of the form for UX reasons, adding a confounding variable that make them much less useful as examples about a purely linguistic point. – SevenSidedDie Oct 08 '14 at 06:37
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    Wow, this is the most up-votes I've gotten for any answer I've posted on this site, and I really didn't see it as all that brilliant or insightful nor was it a lot of work to write. Well, on another Stackexchange site I got my most up-votes for my answer to "What is your favorite programmer joke". :-) – Jay Oct 09 '14 at 13:55
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    I think this is probably the original argument about 0 vs. 1 based indexes :) – David Hayes Oct 09 '14 at 21:23
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    @Qix-MONICAWASMISTREATED Very late follow-up: A philosophical musing: Even if true that a Google sign up form is the most widely used form in the world, that really doesn't give it much more weight than any other form. If that same form mis-spelled a word, I wouldn't say that means that because this form is so widely viewed that that makes this the new correct spelling. If one person created the form, he's still just one person even if the form is widely used. – Jay Dec 10 '21 at 16:30
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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.

tobyink
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    I don't think this is how ordinals work. Your C Arrays link, for instance, says this: "The first element of the array above is point[0]." Note the language: it's zero-indexed, but the first one is number zero. If this really is analogous, then my son might have had birthday zero a couple of weeks ago, but this would have been his first birthday, number 0. – chiastic-security Oct 06 '14 at 18:47
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    Nonetheless, if you say "first birthday", most listeners will assume your son has been alive for 365 (or perhaps 366) days, and if you say "zeroth birthday", people will know what is meant. – tobyink Oct 06 '14 at 19:44
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    Sure, I realise this is how the words are generally used (though I have a feeling people would understand, but also look at me funny, if I said "zeroth birthday"). – chiastic-security Oct 06 '14 at 20:36
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    @tobyink: The purpose of a birthday is not so much to mark a moment in time as to mark the passage of the preceding year. The first birthday marks the end of the first year. This is a different situation from C array indices, which mark the location of the start of array elements. The first array element sits between index 0 and index 1; the next element between index 1 and index 2, etc. – supercat Oct 06 '14 at 22:32
  • @supercat: Off-topic, but in computing, there is a difference between element and subarray. 0-th (first in colloquial speech) element is exactly at index 0; the subarray containing the first element is between 0 and 1. It is the difference between fenceposts and fences between them: the 0-th fencepost is at fencepost #0, but the 0-th fence is between fencepost #0 and fencepost #1. – Amadan Oct 08 '14 at 02:35
  • @Amadan: English has some difficulty with ordinals as applied to mathematics, since the "first" thing should be the one with nothing preceding it. The terms ith and nth may as a consequence be ambiguous. I would say the "first" fence is fence 0, which sits between posts #0 and #1. The "second" fence is fence 1, which sits between #1 and #2. If one regards pointers as identifying the spaces between memory locations, then a *double identifies the 8 bytes following the address, rather than identifying the first byte directly and implicitly identifying the seven beyond. – supercat Oct 08 '14 at 13:55
  • @chiastic-security Note that this is quite a European phenomenon. In many countries not only is your birthday the day you were born, but they also count your age according to the year you're in. So your son would be 1 already if he was born in Korea, for example (he's in his first year!). However, age in Korean even more confusing. It goes by which calendar year you're in. So, if you were in Korea, your son would become 2 on the first of January 2015. This means if a kid is born at 11.30 on new years eve, then s/he's going to be 2 in about half an hour!! :) – Araucaria - Him Oct 10 '14 at 15:33
  • @chiastic-security But in those countries where you are 1 on the day your born, your son's second birthday would be in 2015 as one would logically expect – Araucaria - Him Oct 10 '14 at 15:35
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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 :)

Community
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Pedro Borges
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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.

Colin Fine
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  • That is correct. But do note that the OED article was published in 1887. So the fact that the latest example is from 1858 does not really tell us anything about whether it is obsolete or not. – fdb Oct 06 '14 at 23:00
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"Birthday" is really a shortened form of "anniversary of the day of birth", so the day you are born is not an anniversary of that event. We do use the phrase "birth day" to mean the day of your actual birth.

To add to the confusion, occasionally "birthday" does mean both your birthday and the year of your birth -- on official forms for example -- but you have to allow the context to determine.

A thing to remember is that etymology does not equal meaning. On the contrary, derived words often take on a whole new set of meanings and implications by themselves. For example, the etymology of "pineapple" is plain, however, the resemblance between that fruit and a pine cone or an apple is very limited.

Similarly, the verb "understand" also has a fairly plain and obvious etymology, but the word has a whole world of meanings beyond the original figurative derivation.

In terms of "birthday", etymonline has this to say:

Birthday late 14c., from Old English byrddæg, "anniversary celebration of someone's birth" (at first usually a king or saint); see birth (n.) + day. Meaning "day on which one is born" is from 1570s. Birthnight is attested from 1620s.

I think the reference to the use of religious saints' birthdays is particularly relevant, since presumably they are dead by the time we celebrate their saintliness.

And on the matter of the birth day of your son, congratulations! There is no greater moment that seeing him take his first breath, and you are about to embark on one of the great journeys in life, full of joys, fears, surprises, difficulties, and every human emotion imaginable. I am sure your life is about to become much fuller, and much busier.

I offer you my best wishes on this special occasion of your life.

Fraser Orr
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The anniversary of your son's birth date is your son's birthday. The date of birth of your son, or birth date, is on 23 September 2014.

user3601514
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An example of "birthday" being used to refer to the day of birth is when people say something like: "I was wearing my birthday suit.", meaning they were naked.

That term doesn't seem nearly as clever now as it did before I read this thread.

Conned
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