Updated November 18, 2025

Spotlight on i.e. and e.g. (and etc.)

Latin may be a dead language, but many of its words and phrases flourish in today’s English. The most common Latin borrowing might be an abbreviation: the all-purpose etc., short for et cetera, “and others of the same kind.”

The list of scholarly abbreviations in CMOS 10.48 includes about fifty that are Latin, from ab init. (ab initio, “from the beginning”) to viz. (videlicet, “namely”). Many of these are found primarily in older sources but are included for the benefit of historians and other researchers.

Others, like etc., remain in common use. These include i.e. (id est, “that is”) and e.g. (exempli gratia, “for example”), which are almost as common as etc. But because i.e. and e.g. can both introduce examples, people tend to mix them up. Another common mistake is to pair e.g. with etc.

Read on to find out more.

Specific vs. General*

In Chicago style, the abbreviations i.e. and e.g. are always spelled with periods; they are normally followed by a comma but preceded by either an opening parenthesis, a semicolon, or a dash. In formal prose, their use is limited to parentheses, notes, and tables; outside of those contexts, it is usually best to spell them out (but in English). See CMOS 6.54 and 10.4.

The abbreviation i.e.—as its meaning “that is” would imply—introduces a specific explanation or clarification of the text that immediately precedes it:

When the singular form of a noun ending in “s” is the same as the plural (i.e., the plural is uninflected), the possessives of both are formed by the addition of an apostrophe only.

When a quotation is introduced by an independent clause (i.e., a grammatically complete sentence), a colon should be used.

Sometimes the clarification will consist of one or more examples:

Before entering the room, we were asked to turn over any items that might be attracted to a magnet (i.e., jewelry, keys, and anything else with metal).

The abbreviation e.g., on the other hand, always introduces one or more examples (as its meaning “for example” suggests). Unlike items introduced by i.e., these examples provide a general, open-ended illustration rather than a more specific clarification:

Titles of larger works (e.g., books, journals) are usually italicized, whereas titles of smaller works (e.g., chapters, articles) are presented in roman and enclosed in quotation marks.

In index entries, use an en dash rather than a hyphen in inclusive page numbers (e.g., “dogs, 135–42”).

Use etc. with i.e. (maybe) but not with e.g.

The best way to remember whether etc. should be used with i.e. or e.g. is not to use it at all. That’s because etc. should never be used with e.g., and it would only rarely be a good choice with i.e.

For example, you might be tempted to use etc. in the magnet example from the previous section:

Before entering the room, we were asked to turn over any items that might be attracted to a magnet (i.e., jewelry, keys, etc.).

But the original wording (“and anything else with metal”) is better because it’s more specific than etc. If you want to keep things general, use e.g. and limit what follows to examples (without tacking on an etc.):

Before entering the room, we were asked to turn over any items that might be attracted to a magnet (e.g., jewelry and keys).

not

Before entering the room, we were asked to turn over any items that might be attracted to a magnet (e.g., jewelry, keys, etc.).

It’s understandable that you’d want to add an etc. to what follows e.g., but resist the urge. The words for example imply the existence of other examples of the same kind—which is literally the meaning of etc. (as we learned at the beginning of this post). In other words, etc. is built into e.g., so adding etc. after the examples would be redundant.

Key Points

To summarize, use i.e. for clarifications and e.g. for examples; avoid pairing etc. with e.g.; and if you’re tempted to use etc. with i.e., it’s usually best to be more specific.

* Versus is another Latin borrowing, abbreviated v. in the names of court cases (see CMOS 8.83) but often vs. in other contexts (as in the heading to which this footnote pertains and throughout the index to CMOS).

Top image by Karen Roach (modified for post) / Adobe Stock.

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