I'm not English so I find it hard to guess the reason why "Not in a month of Sundays" means "It won't happen" or "A long period of time".

I find the meaning weird. Can anybody explain to me why it means this? My question is why.

Full context (A children's literature by Jacqueline Wilson):

But my mum's coming to see me at Christmas. She is. I just know she is. 'Your mum's not coming to see you in a month of Sundays,' said Justine Littlewood. 'Your mum's never ever coming back because she doesn't want anything to do with an ugly manky bad-mouthed stupid show-off who wets the bed every ni—' "*

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    Comments are not for extended discussion; this conversation has been moved to chat.
    – tchrist
    Commented Jul 12, 2018 at 2:33
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    (see above). Fair warning: unfortunately, it is not technically practical for moderators to perform more than one migration from the comment thread to the chatroom. So further discussion here will simply be deleted.
    – MetaEd
    Commented Jul 13, 2018 at 20:35
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    Because broadly, "a month of Sundays" means 30 Sundays in a row. Not entirely impossible but how likely could that really be, please? Commented Jul 16, 2018 at 19:15

11 Answers 11


According to the following source it probably derives from the Christian concept of Sunday as a "day of rest" from which the notion of a very long time:

  • The expression is said to mean 30/31 weeks (the amount of time it takes a month of Sundays to pass) and has is believed to have origins from the Christian Holy Day of Sunday, the Sabbath. This day was a “day of rest” and was a long, solemn day devoid of amusement. Activities were even regulated on Sunday by law at times and therefore Sunday could seem long and tiresome (out of boredom)… therefore a month of Sundays could feel like an eternity. It is also sometimes used to denote something that will never happen.

The Oxford English Dictionary cites the first printed use of the phrase from 1759:

  • “The commander..swore he should dance to the second part of the same tune, for a month of Sundays.” H. MURRAY Life & Real Adventures Hamilton Murray I. x. 121

NOTE: There are some variations on this, such as: Week of Sundays, Week of Saturdays, etc.


  • Comments are not for extended discussion; this conversation has been moved to chat.
    – MetaEd
    Commented Jul 13, 2018 at 20:31
  • Let me phrase this as a question rather than a quibble. :) I don't have easy access to the OED right now (my library doesn't subscribe to the online version) — in addition to the citation, does the OED support the "30/31 weeks" explanation?
    – mattdm
    Commented Jul 15, 2018 at 13:52
  • @mattdm: The OED supports the "7 weeks" meaning for "a week of Sundays". But it's impossible to know if this is the original etymology or a later interpretation. Commented Jul 15, 2018 at 22:39
  • @Peter Can you quote it? I'm super curious.
    – mattdm
    Commented Jul 15, 2018 at 23:08
  • @mattdm: the OED says: "a week of Sundays: (colloq.) seven Sundays; seven weeks; (hence) a long or indefinite period of time. Often in negative contexts, esp. as not in a week of Sundays: never." However, note that a month of Sundays is by far the older expression, and the OED doesn't say that means 30 weeks. Commented Jul 16, 2018 at 0:26

Two of the first citations (1841 and 1849) I find [in Google Books] for it are

I would give you a month of Sundays and you could not guess; so I will tell you.

He would not guess it in "a month of Sundays," neither shall we enlighten him.

My guess is that it started with expressions much like these.

Since Sunday is a day where you don't have to work, a month of Sundays is a whole month where you don't have to work. Thus, this means that he could have a whole month where he could devote all of his time to guessing this answer, and he still couldn't do it.

And a similar usage from 1835:

Your money I'll hide so that, if they were to search for a month of Sundays, by Jasus ! they'd never find it.

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    I'd never encountered the phrase before, and this is exactly the meaning I took from the context. Commented Jul 11, 2018 at 23:49
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    In addition to being logical (and what I have always taken it to mean as well), this fits with the example in the question itself. If the whole month were comprised of Sundays, presumably her mum could find the time to come visit.
    – GHolmes
    Commented Jul 13, 2018 at 16:14

There's a similar idiom in French:

"La semaine des quatres jeudis".

A literal translation would be : "The week with 4 thursdays". It means some time that you might wish for (there was no school on thursdays until the 1970s) but will never happen : no week will ever have 4 thursdays, just like no month will ever be full of Sundays.

It doesn't mean that the event is unlikely or might happen in a very long time. It will never happen.

This expression appeared in Rabelais' work 5 centuries ago. It is well known in French, and it might have inspired "Never in a month of Sundays" since the English idiom appeared much later.

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    IMHO This. I am not English native, but when I read the phrase "month of sundays" the first thing to come in my mind was: There'll never be one. Also, the choice of sunday is because of a day off in Christianity. The "not" in "not coming [even] in a month of sundays" is an emphasize. Commented Jul 12, 2018 at 5:58
  • Thinking on it more, I like your answer but it doesn't really answer the question because of the very important word "of". If it was "a month with Sundays" the speaker would be using an idiom almost identical to "a day ending in y", but the other high rated answers explain the feeling of eternity intended by the "month of Sundays".
    – Dispenser
    Commented Jul 12, 2018 at 16:10
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    @Dispenser Every month is a month with Sundays. A month of Sundays means that every day of the month is a Sunday. Commented Jul 13, 2018 at 5:44
  • Really? Surely then the phrase would be "Only in a month of Sundays" or something? As in it would happen only in a month full of sundays (therefore it'll never happen), similar to "Once in a blue moon". I feel like the "Month of Sundays is a very long time" interpretation is more correct, as in, it will never happen, even if a month of sundays pass.
    – komodosp
    Commented Jul 13, 2018 at 10:24
  • @colmde "in a month of only Sundays" would be the same, not "only in a month of Sundays". The calendar is defined in a way that there will never be a month of Sundays. A blue moon occurs about twice a year. Commented Jul 14, 2018 at 10:47

"Month of Sundays" is an idiom that means "an indeterminately great length of time."

You ask why it means that, but there isn't really an answer. An idiom is an expression that means something other than the actual words when taken separately would seem to mean.

While it's not known why the expression means what it means, because the author who coined the expression, Hamilton Murray, never explained himself, one theory is that it's referring to about thirty weeks as seeming like a very long period of time, a month of Sundays or approximately thirty Sundays requiring approximately thirty weeks to pass to achieve.


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    @Billy Although the OED is not a "General Reference" material (because it requires a subscription) it does support the theory you refer to. It cross-references a week of Sundays and writes: seven Sundays; seven weeks; (hence) a long or indefinite period of time. Often in negative contexts, esp. as not in a week of Sundays: never. Cf. a month of Sundays at Sunday n. Commented Jul 11, 2018 at 6:50
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    You ask why it means that, but there isn't really an answer. An idiom is an expression that means something other than the actual words when taken separately would seem to mean. Just because an idiom is not to be taken literally doesn't mean you can't explain an idiom by explaning its literal meaning. "I'll have your guts for garters" isn't literal, but you can still explain that it means that the speaker will viscerally (pun intended) assault the person being spoken to.
    – Flater
    Commented Jul 11, 2018 at 12:35
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    @Flater - You've given me an undeserved dressing down. If you had kept reading past the point you cited, you'd have seen I didn't simply leave it at that. In the next paragaraph, I say that it's not known why it means what it means, which I arrived at through research, and the reason why it's not known is the expression was coined by Hamilton Murray, who explained what it means but didn't explain why it means that. I then provided the prevailing theory of why but explained that it is pure conjecture, meaning its not based on any historical facts or records, just guesses.
    – Billy
    Commented Jul 11, 2018 at 13:24
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    @AnthonyGrist It is not very difficult to join one. I think most local authorities still provide library services. Just call in and ask if they have an OED subscription, and if so, could you join? My library card has a unique 16 digit number which I simply enter as my log-in to both OED and ODNB. Cost £O. But I do pay my Council Tax!
    – WS2
    Commented Jul 11, 2018 at 14:37
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    Are you clear on how Hamilton is using the phrase? I've been reading the original quote, and can't tell how it should be parsed.
    – 1006a
    Commented Jul 11, 2018 at 14:39

You have explanations about the origin but there is no definitive answer as to why.

People like to create phrases such as this in order to add weight to what they are saying and simply to have fun with the language.

For example, why say "He's not the sharpest tool in the shed" when you can say "He's an idiot". One is direct and shorter, the other is colourful, amusing and perhaps not quite so insulting.

There are many reasons for adding such constructions as this.


No one really knows why, but the Oxford Dictionary of Idioms and Oxford Dictionary of Word Origins offer the suggestion that it is related to religious restrictions on activities on Sunday.

Many people seem to have taken hold of an often-repeated (on blogs, forums, and such) claim that this "literally" means either 7 weeks or 30 weeks. I can accept that some people use the expression that way, because, hey, it's an expression, but I'm at a loss to see how people are painting that as "literal", because literally a month is 28, 30, or 31 days and has 4 or 5 Sundays. "A month" isn't a generic container word for 30 of something, and "a Sunday" isn't a literal word for "a seven-day period".

Many of the answers seem to imply some dictionary authority for this as "literal". It's true that dictionary.com says the above, but it's pretty short with no explanation or references of its own. The Oxford Dictionary of Idioms says:

a month of Sundays a very long, seemingly endless period of time

This expression may be a reference to the traditionally slow passage of Sundays as a result of religious restrictions on activity or entertainment. In a letter written in 1849, G. E. Jewsbury talked of the absence of mail deliveries on Sundays, remarking: 'If I don't get a better letter from you ... you may pass "a month of Sundays" at breakfast without any letter from me'.

Similarly, the Oxford Dictionary of Word Origins says:

Where Christianity was the dominant religion, restrictions on pleasure and activity meant that Sundays were quiet, private days. This may be behind the expression a month of Sundays, 'a very long, seemingly endless period of time'. The expression is known from 1836 in The Clockmaker by Thomas Chandler Haliburton: 'Mr. Slick ... told him all the little girls there would fall in love with him, for they didn't see such a beautiful face once in a month of Sundays.'

Neither of these try to stretch the phrase into some sort of arithmetical equation. The literal interpretation that makes sense of the words is "a month [comprised] of [only] Sundays" — which of course is also nonsensical, but at least it's actually literal. But of course, it's an idiom, so the literal meaning is only slightly helpful in the first place — the "why" is going to be in the figurative meaning, and for that it seems we can only guess.

The explaination the Oxford dictionaries offer, "Sundays are long and without activity, so a whole month of those feels like a lot", seems logical enough.


I'm going to share how I've always interpreted this idiom, which differs from the well-researched, documented and cited explanations which have been posted: Whenever I've seen it, it's always related to a task that needs to be done in someone's spare time (or perhaps, "personal" time would be better). Like a hobby, or a home-improvement job, for which a nice free Sunday is the only time one can find to work on it. This is obviously in the context of the five- or six-day work week in which the weekend, and especially Sunday, is the day of the week free for personal initiatives; a paradigm of western-world industrialization.

So if a task is particularly labour-intensive, or unpleasant, or of very low relative priority, then you are unlikely to get it done, even with 30 Sundays in a row (or 31, etc.).

I accept that this is likely not how the idiom was coined, but I'll bet I'm not the only one who's been using it with this perspective. Does this fit the context in which you've seen it used?

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    Ah, but this is a modern, post-Christian interpretation of what Sunday is. Sunday, post-Reformation, wasn't a personal day; Sunday was the Lord's Day. You take a break from your wordly worries and labor, but also from your worldy recreations and distractions. If the Puritans have anything to say about it, Sunday is for employing your body in formal and informal forms of worship and your mind in pious thought. Even in the early 20th century, strict Sabbatarians of various denominations were condemning the Sunday playing of golf as well as films on Sunday.
    – choster
    Commented Jul 11, 2018 at 14:54
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    This was always my interpretation too. Sunday is the day you get things done because you're not at work. In the 19th century, when the term came about, it was the only day you wouldn't be at work. The answer really needs a citation though or it's just speculation.
    – Richard
    Commented Jul 11, 2018 at 14:55

I have always taken "not in a month of Sundays" to mean that someone doesn't want to do something rather than that something won't happen.

As the traditional day of rest (in many western countries), and because of restrictions on businesses on Sundays they are often considered a day to not do very much, laze about, and have time to get bored. The idea is that if you had a month of them in a row you would start feeling like you would do anything (including things you previously wouldn't want to do) to not be bored, and therefore something you wouldn't do even at this point of boredom must be really bad.


The literal meaning is just "A week for every day in a month", (i.e. "seven months" or alternately "30 weeks"), but expressed in a comical fashion to import a connotation that it is not to be understood literally.

Compare "Shedload". A shed is a thing which you could load with goods, so it has a literal meaning "the amount you could fit into a shed", but it's expressed in a comical way to signal that it is not literal, and just means "a lot, probably more than you would expect", whilst also adding humour and possibly improving the meter of the sentence, adding to the imagery, etc.

Similarly "a month of Sundays" just means "a very long time" whilst also adding humour, contributing to meter, rhyme, and imagery, etc.

  • I think Mark Twain has a Huck Finn talk about a "week of sundays" as a literal term for a couple of months, more or less. This would correspond to this exactly, while making a month of sundays 30 weeks, i.e. close to a year, i.e. takes forever. Commented Jul 12, 2018 at 20:55
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    This is the right answer, not sure where all the confusion is coming from in the other answers. Commented Jul 13, 2018 at 6:40
  • I don't see how that is a natural reading as "literal meaning". We don't use "a month of X" to mean 30 of X — and we also don't generally use Sunday as a stand-in for "week". The natural literal meaning to me is "a month in which every day is a Sunday".
    – mattdm
    Commented Jul 13, 2018 at 16:20
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    @Joel: I've looked at every single instance of the word Sunday(s) in Tom Sawyer and Huckleberry Finn, and I can find no mention of "a week of Sundays". Commented Jul 13, 2018 at 18:16
  • Ok, I guess not Mark Twain, but it is definitely an "old timey" expression that is almost certainly archaic now. We had to have the teacher explain what it meant as well, so clearly it has been "lost" to common knowledge. Commented Jul 20, 2021 at 23:12

Other answers provided great explanation what "month of Sundays" is. However, I feel like your question is more about "not" part fitting the phrase.

The truth is that not isn't part of the idiom here, but is simply a part of the Your mum's not coming to see you phrase.

It goes like this:

  • Your mom will not come to visit you.
  • Your mom will not come to visit you even if she got the whole month off.

Replacing the month off with an idiom gives: Your mom will not come to visit you even in a month of Sundays

or Your mum's not coming to see you in a month of Sundays


As per user110518's answer, Christian people traditionally did nothing on a Sunday, it instead being reserved as a day of rest.

So if I say Croatia will not beat England in the World Cup Semi-Final in a month of Sundays, I'm saying it will not happen, just as nothing happens on Sundays.

Whether I'm imagining this event not happening in a month of say 30 or 31 consecutive Sundays, or just for each Sunday spread over the course of say 30 or 31 weeks, is irrelevant as the meaning is the same.

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