Hyphens, En Dashes, Em Dashes

Q. I understood that compounds formed with prefixes are normally closed. However, I see a hyphen used on television and in print with all sorts of prefixes—for example, “co-founder” or “non-violent.” Are compounds formed with prefixes still normally closed? Or has spellcheck run amok?

A. Don’t worry, compounds formed with prefixes are still usually closed (see our hyphenation guide, section 4, under CMOS 7.89). But the truth about hyphens is that they tend to make compounds more legible rather than less. The deconstructionists understood this when they used a hyphen to show that the apparently straightforward act of re-membering involves piecing together the fragments of the past. But use hyphens sparingly, and only when they are truly needed. Chicago advises retaining a hyphen to prevent a doubled a or i (“intra-arterial,” “anti-intellectual”) and for certain words that might look odd without one (“pro-life,” “pro-choice”). A hyphen is also required next to a proper noun (“sub-Saharan”) or a numeral (“pre-1950”). In rare cases, a hyphen can distinguish between two meanings of a word (“recreate” vs. “re-create”). And though “cofounder” is frequently hyphenated (“co-founder” is the second-listed of equal variants in Merriam-Webster), “nonviolent” is more likely to appear closed—and neither requires a hyphen in Chicago style.