Born on the same day

Today is the birthday of my second mother-in-law, Monique Serpette Transue (born 1912). And also of Samuel “Dictionary” Johnson (born 1709). A coincidence of dates that entertains me. When I noted this on Facebook yesterday, Ned Deily wrote:

The interwebz assert that no single word exists, in English at least, to describe people who share the same birthday anniversary. Time to invent one? A lexicographer’s work is never finished.

After a digression on what lexicographers do and another on Samuel Johnson and a note about Gilbert du Motier, the Marquis de Lafayette, I’ll make a stab at coining.

Lexicography and word coining. Lexicographers are in the business of recording the uses of words and phrases; they are not inventors. Lexicography is a challenging technical profession, and I am not a lexicographer, not qualified to be one (though I hang out with lots of lexicographers and am happy to provide them with material for their work and to use the fruits of their research). On their side, lexicographers have to know a good bit of linguistics to do their job properly.

There are people whose business it is to coin words, specifically trade names in various domains — one part of the larger enterprise of branding products. Again, this is a surprisingly technical and complex exercise; people who work in the area tend to be drawn from lexicography and linguistics, but the work requires an apprenticeship all on its own.

Otherwise, words are coined by ordinary people in individual acts of invention, often thoughtlessly, but sometimes with explicit thought. Most coinages vanish quickly; only a few catch on and spread, in the fashion of all sorts of linguistic innovations.

Samuel Johnson. From Wikipedia:

Samuel Johnson (18 September 1709 [OS 7 September] – 13 December 1784), often referred to as Dr Johnson, was an English writer who made lasting contributions to English literature as a poet, playwright, essayist, moralist, literary critic, biographer, editor, and lexicographer. Religiously, he was a devout Anglican, and politically a committed Tory. The Oxford Dictionary of National Biography describes Johnson as “arguably the most distinguished man of letters in English history”. He is the subject of James Boswell’s The Life of Samuel Johnson, described by Walter Jackson Bate as “the most famous single work of biographical art in the whole of literature”.

The Marquis de Lafayette. From my 9/7/19 posting “Big sexy prime birthday gay ice cream”, with a section on Lafayette:

A man of enormous physical courage who took up the family military career at the age of 13 and later pursued an extraordinary public career devoted to advocating for democracy and human rights in two countries, and managed somehow to live to the age of 76.

I am pleased to share a birthday with him (9/16: me in 1940, him in 1757).

Birthday-sharer. To judge from comments on the net, birthday twin would appear to be the only term with any currency at all. But the more semantically transparent birthday-sharer would be the obvious N + N compound in English for referring to someone who shares your birthday. So, yes, birthday twin and birthday-sharer are words — but as compounds, both are composed of two words. If you really insist on a single word, you’re probably going to have to look to the ‘birth’ words in the classical languages: stems gen– in Greek, nat– in Latin. In combination with the ‘with’ prefixes syn– from Greek, co(n)- from Latin. So: syngen(e)ic or co-natalist.

Some complexities.The Greek term already has a use, which is related to the meaning we’re after, but significantly different from it. From Wikipedia:

The word “syngenic” or “syngeneic” (from the Greek word for a relative) means genetically identical, or sufficiently identical and immunologically compatible as to allow for transplantation. For example, it may be used for something transplanted from an identical twin. When the cells are collected from the same patient on whom they will be used, it is called autologous and when collected from identical individuals, it is referred to as syngeneic.

The word is an adjective, but of course it can be used as a noun as well, to refer to ‘something syngen(e)ic’. And the existing word is a highly technical term, not likely to be familiar to most people, so a homophonous noun a syngenic ‘a birthday-sharer’ should be unproblematic.

The Latin term co-natalist incorporates an existing English term, with a lot of social baggage attached to it. From Wikipedia:

Natalism (also called pronatalism or the pro-birth position) is a belief that promotes the reproduction of human life. The term comes from the Latin adjective for “birth”, nātālis.

Natalism promotes child-bearing and parenthood as desirable for social reasons and to ensure the continuance of humanity. Natalism in public policy typically seeks to create financial and social incentives for populations to reproduce, such as providing tax incentives that reward having and supporting children. Adherents of more stringent takes on natalism may seek to limit access to abortion and contraception, as well.

Given natalism, we automatically get an adjective and noun natalist, so that a prospective noun co-natalist ‘birthday-sharer’ bears some risk of calling up the noun natalist ‘promoter of child-bearing and parenthood’.

Co-natalist was my first thought as a coining for ‘birthday sharer’ — it seemed a lot more transparent than syngenic — but now I’m not so sure. One possibility would be to clip it, to a new noun co-nate (“my co-nate Lafayette”).

Of course, all this invention is beside the point if people are content to say things like “I have the same birthday as Lafayette” or “I share a birthday with Lafayette” and leave it at that. Just because we could have a single word doesn’t mean we actually feel a need for one.

9 Responses to “Born on the same day”

  1. Julian Lander Says:

    I have to admit it’s not a term I would have much use for. But I’m also concerned about potential confusion as to whether the date includes the _year_. When well-known historical figures, such as Lafayette, are involved, there is no issue, because of the obvious disparity in age. But do we need a second term, one for sharing both day and year, and one for the day only. It may not be obvious to the listener that when I say I share a birthday with Karl Rove, I mean the date only, not the year. (When I say that I share one with Isaac Newton, the ambiguity is resolved, although there’s a calendar problem there, so it’s only the nominal date that matches.)

  2. RF Says:

    C’est un annivershared ? (works better if you pronounce the first half the French way)

  3. arnold zwicky Says:

    For Dr. Johnson’s birthday, John McIntyre has now provided a significant quotation from him on usage:

    “Words being arbitrary must owe their power to association, and have the influence, and that only, which custom has given them.”


    I vote for co-natalist. I don’t think the existing scientific term syngenic or syngeneic is all that rare. My favorite co-natalist is Pete Seeger, exactly 20 years older than me. I met him briefly once.

    Lots of luck introducing a new word into the English language, a feat that’s long been on my bucket list. I’ll start with syncopresis, a polite way of saying ‘getting your shit together’. I have a good many more.

    I’ve long sought a word to describe two years that begin on the same day of the week. 2020 is isebdomadal (isebdomadary?) with 1953. No such word – and I’ve been looking for a long time.

    More than 40 years ago I dated a woman who was born the same day I was – she’s five hours older than me. Her first name’s Xonia. I think she should have a hurricane named after her.

    • arnold zwicky Says:

      “Lots of luck introducing a new word into the English language”. I am NOT trying to introduce a new word; in fact, I pointed out the problems with trying to do that. I’m just saying that if you want a word, here are some possibilities

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