Hyphens, En Dashes, Em Dashes

A. CMOS prefers the actual minus sign, which is not the same as an en dash, in professionally typeset material. The minus sign is defined by Unicode as U+2212; the en dash is U+2013. See paragraph 11.2 and table 12.1 in CMOS for more information.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. All prefixes form words that are closed unless the word it is joined with is a proper noun, or if there would be ambiguity owing to, for example, a doubled letter, or if the hyphenated version is in the dictionary:

autoloading

auto-destruction [hyphenated, I would suppose, because it is analogous to self-destruction]

autobus

auto-ovulation [to avoid double o]

auto-Nietzschean

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. I think an analogy is appropriate, here. Canton is in Ohio. Therefore, Canton, Ohio. The University of California’s East Bay institution is in Berkeley, California. So, it’s the University of California in (or at) Berkeley, or the University of California, Berkeley. I can see an en dash being used as well, because an en dash can join one word to a compound, as in “a jazz–rock ’n’ roll hybrid” (where the en dash joins “jazz” to “rock ’n’ roll”). Berkeley needs to be joined to the entire “University of California,” so an en dash would work, but not a hyphen. By the way, the University of California prefers the comma.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. You have it right. The idea is that you are “developing short-term, medium-term, and long-term steps for” something, but that you want to avoid repeating “term,” so you simply delete the first two instances of “term”; et voilà: now you are “developing short-, medium-, and long-term steps.”

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. I will try to condense the various bits of information scattered throughout CMOS. First of all, there are three lengths of what are all more or less dashes: hyphen (-), en dash (–), and em dash (—). I frame it this way because the work they do is roughly related to their length (though I don’t think CMOS puts it this way outright).

The hyphen connects two things that are intimately related, usually words that function together as a single concept or work together as a joint modifier (e.g., tie-in, toll-free call, two-thirds).

The en dash connects things that are related to each other by distance, as in the May–September issue of a magazine; it’s not a May-September issue, because June, July, and August are also ostensibly included in this range. And in fact en dashes specify any kind of range, which is why they properly appear in indexes when a range of pages is cited (e.g., 147–48). En dashes are also used to connect a prefix to a proper open compound: for example, pre–World War II. In that example, “pre” is connected to the open compound “World War II” and therefore has to do a little extra work (to bridge the space between the two words it modifies—space that cannot be besmirched by hyphens because “World War II” is a proper noun). Now, that is a rather fussy use of the en dash that many people ignore, preferring the hyphen.

The em dash has several uses. It allows, in a manner similar to parentheses, an additional thought to be added within a sentence by sort of breaking away from that sentence—as I’ve done here. Its use or misuse for this purpose is a matter of taste, and subject to the effect on the writer’s or reader’s “ear.” Em dashes also substitute for something missing. For example, in a bibliographic list, rather than repeating the same author over and over again, three consecutive em dashes (also known as a 3-em dash) stand in for the author’s name. In interrupted speech, one or two em dashes may be used: “I wasn’t trying to imply——” “Then just what were you trying to do?” Also, the em dash may serve as a sort of bullet point, as in this to-do list:

—wash the car

—walk the dog

—attempt to explain em and en dashes

This explanation is not intended to be exhaustive (for much more, see chapter 6 in CMOS), but I do hope that it helps to frame the different potential of each length of dash.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]

A. Chicago hyphenates all “free” words in any position: toll-free call; the call was toll-free. See CMOS 7.89, section 3, under “free.”

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]