I.e. is used when we would like to use a situation as a kind of clarification.

Suppose I was to write something like this:

Nano-boxes are used in medical science i.e. cancer treatment, where the nano-boxes are used to inject drugs into cells.

The problem, however, is that I would like to refer to an example regarding the cells. How would I write it? Like this?

Nano-boxes are used in medical science i.e. cancer treatment, where the nano-boxes are used to inject drugs into cells i.e. cancer cells.

However, I've been told that you cannot have an i.e. within an i.e.

Are there suggestions on how to write it?


"i.e." - which stands for "that is" - in this context is incorrect. If you provide an example to clarify your statement, you probably should use "e.g." - "for example".

Something like

Nano-boxes are used in medical science e.g. cancer treatment, where the nano-boxes are use to inject drugs into cells e.g. cancer cells.

"i.e." is usually used when you provide a paraphrase of your previous words, i.e. say the same thing in different words

Here's a wiki article on using both abbrevations:http://www.wikihow.com/Use-%22i.e.%22-Versus-%22e.g.%22

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  • Is i.e. latin? I always guessed at it meaning 'in example' ;P – Garet Claborn May 23 '11 at 14:22
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    @Garet Claborn: "i.e." stands for "Id est" - which is Latin for "that is"; whereas "e.g." stands for "exempla gratis" - "for example". – Piskvor left the building May 23 '11 at 14:28
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    @Piskvor: It is exempli gratia. – Cerberus_Reinstate_Monica May 23 '11 at 15:03
  • @Cerberus: Thank you for the correction, my Latin is quite rusty. – Piskvor left the building May 23 '11 at 17:10

My self-made mnemonic from childhood was:

i.e. = In Eother words (in other words)

e.g. = egzample (example)

Your uses are examples, effectively because they're one of many possible options, so "e.g." is appropriate. "i.e" is used where you're rephrasing what came before.

As to rewording, my suggestion is the same as @Alenanno's, which arrived while I was typing this.

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  • Well, nice mnemonic method! :D – Alenanno May 23 '11 at 9:07

In order to avoid your problem completely, what about rephrasing your example like this:

"Nano-boxes are used in medical science, such as cancer treatment, where the nano-boxes they are used to inject drugs into cells, e.g. cancer cells."

This way, you don't use i.e.'s or e.g.'s too much, which inhibit the flow of reading, and it also eliminates your problem of having nested abbreviations.

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  • I'd prefer to use like instead of such as here, because personally I feel such as should follow with multiple items, e.g., such as xxx and yyy, etc. But I'm not sure. – Xiè Jìléi May 23 '11 at 9:03
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    Using such as with a single example is perfectly acceptable though. :D – Alenanno May 23 '11 at 9:05
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    I'd use "such as" in order to avoid the pairing of "like" and "cancer": though it wouldn't seem strange in context, it's the kind of thing that catches my eye when scanning a page. – Matthew Frederick May 23 '11 at 10:36

I endorse what everyone else has said about using e.g. rather than i.e.. However, even Alenanno's rephrasing of the sentence you were asking about doesn't read smoothly.

The problem is that you are in effect interpolating one example into two places in the sentence, so the reader never gets used to one context before having to switch to the other. It would be better to separate the example out entirely to avoid that:

Nano-boxes are used in medical science to inject drugs into cells. For example, in cancer treatment they are used to target cancer cells.

Notice that the sentence with the example isn't an exact repeat of the sentence with the general explanation. Writing "inject drugs into" instead of the italicised "target" draws attention to the repetition rather than the information it's trying to convey, so it helps to rephrase just a little.

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  • +1. I was about to suggest that the second e.g. be dropped, but breaking the example into its own sentence to unify the thought is even better. – Wayne May 23 '11 at 13:00

As i.e. means "that is (to say)" and I think there is no hard rule that forbids multiple occurrence in the same sentence and that this is a suggestion that concerns style and readability.


Alennano gives a good suggestion regarding style; similarly I would suggest even

Nano-boxes are used in medical science to inject drugs into cells, e.g into cancer cells in cancer treatment.

This is a rather small change compared to Alennano's answer, but I believe there is one difference worth thinking about - here you really have a single example, where in original you have two connected examples.

One could argue that it is always possible (and maybe even always desirable) to (logically) simplify multiple occurrences of i.e. or e.g. into single occurrence and this might have been what you have originally been told ("...i.e. within an i.e.").

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  • Yes, if you have examples twice in a sentence, you might consider using a single example sentence instead, either integrated or following what you just said with a "For example". – Kit Z. Fox May 23 '11 at 11:57
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    It's just "that is", not "that is to say" – Mario May 23 '11 at 15:14
  • @Mario, if you translate directly from latin you are right; however the phrase "that is to say" is suggested as appropriate English translation. thefreedictionary.com/i.e. etymonline.com/index.php?term=i.e. – Unreason May 23 '11 at 15:29
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    it is perhaps "appropriate." However, you suggested that "that is to say" was what it "literally means." You might want "id dicere est" or "quod dicere est." – Mario May 23 '11 at 15:38
  • You are right, literally is wrong there, will edit. Thank you. – Unreason May 23 '11 at 15:56

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