I have the following sentence:

There are two two-dimensional shapes.

The double occurrence of the word "two" (one to indicate the amount of shapes and another to indicate the amount of dimensions) seems confusing to my eyes. Is it correct to insert a comma to separate the double occurrence?

There are two, two-dimensional shapes.

I haven't been able to find this usage rule for commas anywhere, but I could have been looking in the wrong places.

  • If you replace "two-dimensional" with "flat", you'll see that the comma doesn't make sense: "There are two, flat shapes." While commas can be used in lists of adjectives, it's only for adjectives which could reasonably be moved around without impacting the meaning. E.g. "There are two red, flat shapes" and "There are two flat, red shapes" are both OK, whereas "There are flat[,] two shapes" is incorrect (with or without the comma).
    – nollidge
    Oct 5, 2018 at 17:39

3 Answers 3


No, you should not do this. These sentences are correct:

"There are two two-dimensional shapes."

"She has six six-sided die."

"That was a very late late-night game!"


It's not easy to prove a negative but that's not a natural place for a comma and I've never seen a decent argument for using one. You're right that the example sentence is less than ideal, and it's not as easy as some other examples to reword. You still could though:

  • There are two (two-dimensional) shapes (the brackets surround a clarifying adjective that's can be omitted without breaking the sentence, especially as shapes are normally 2D otherwise they'd be solids)

  • There are two shapes, both two-dimensional

  • There are two 2D shapes or there are two 2-dimensional shapes (unless there's an applicable style authority saying that single digits aren't allowed, clarity is better served by using them here, though the abbreviation may not be appropriate)


I understand why it looks unpleasant to you. But, no, a comma is not warranted. Instead, you might want to recast the sentence. One solution could be to use bidimensional instead of two-dimensional.

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