"Buy her that one thing she won’t buy for herself."

I noticed "...that one thing..." is a very special usage here, where as a non-native speaker I would make a sentence almost same (but without "ONE")". So, I would simply say "Buy her that thing she won’t buy for herself"

But, I wonder why the writer might have used (...THAT ONE THING... rather than "THAT THING"). Do you think he did it;

a) because he wanted to mean "If there are many things that she couldn't afford, buy only one such a thing for her, but one is enough so buy one, NOT two, NOT three, not FOUR etc.",

b) or rather than the number of the things, he wants to refer to the "degree of her LIKING. The writer may have wanted to use it "THAT ONE THING" which people commonly use when pointing at the things they liked at the shop windows, eg "THAT ONE on the right, THAT ONE over there". So, maybe the writer used it to refer to the MOM's possible sentence when pointing at "THE PRODUCT" she liked most. (when she was out looking at the windows, she said she liked THAT ONE the most and you asked her "which one?" and she pointed at it saying "THAT ONE"? May be the writer wanted to quote her.

So, really, why "THAT ONE THING" instead of "THAT THING"?

  • 1
    It's just for emphasis - speaker thinks there is (or at least should be) one single thing that fits the bill here. Compare and contrast with "non-emphatic" Buy her something she won’t buy for herself (there could be many such things - just pick any one you like). Commented Sep 5, 2022 at 12:30

2 Answers 2


There's a difference between British English and American English, here.

American English speakers tend to add 'one' in quite often - for example, "that one time...", "that one guy...", "that one movie..." - and for the most part it is completely superfluous. When you're speaking about a specific occasion, person, thing, or whatever, you don't need to further specify its uniqueness.

When British English speakers say this it is usually a slightly different context and is said to make it clear that the thing referred to is the only one possible answer. So, your example of "that one thing she won't buy herself" would mean that there is only one thing she would never buy for herself and it is known what that thing is. We are also probably more likely to say "the one thing...".

  • Superfluous? I think US speakers insert that "one" where we might use some sort of circumlocution "I do seem to recall..." etc. so their "one" is still expressive of something. I would agree that our "the one thing..." strongly suggests the only thing, although when I say "the one thing I won't stand for" there are certainly multiple things I cannot abide, but this one takes the biscuit.
    – Deipatrous
    Commented Sep 7, 2023 at 14:22
  • @Deipatrous I think it would be remiss not to note that it could be superfluous. For example, I could say "the one thing I wasn't expecting was for Deipatrous to look through my old answers from over a year ago and start commenting on them", but it wouldn't be true because there are probably many things I'm not expecting. I'm not expecting to find a dancing octopus in my garage. It's just a figure of speech for emphasis in many cases. "That thing" is singular - it can't be more than one anyway.
    – Astralbee
    Commented Sep 7, 2023 at 15:40

"That one thing" or "the one thing" is used for emphasis. It means something like "the most of all things", or "the single most thing", or sometimes even "the only thing". It's a fairly common expression, and slightly idiomatic, so it's not easily understood if you are not familiar with it.

Another example

That was the one thing that I didn't want to happen.

To paraphrase: Of all the things that could happen, that was the one which I really did not want to happen.

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