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Hyphens, En Dashes, Em Dashes
Q. I know that the CMOS preference is not to hyphenate “noun + gerund” compounds, but in the case of “decision-making,” which appears with the hyphen in many dictionaries, would CMOS call for a hyphen? Thank you in advance!
A. Here’s what our hyphenation table says, under “noun + gerund”: “Noun form usually open; adjective form hyphenated before a noun. Some permanent compounds hyphenated or closed (see 7.82).”
If you follow the link to paragraph 7.82, you will see that a permanent compound is a compound that’s listed in the dictionary in any form—open, hyphenated, or closed. In Merriam-Webster, our dictionary of choice, the hyphenated compound noun “decision-making” appears as such, so it’s always hyphenated. (Most adjective forms, on the other hand, can be left open after a noun, even if they are listed in the dictionary with a hyphen.)
In CMOS 16 (published in 2010), “decision-making” was not yet listed in Merriam-Webster. But M-W added it in time for CMOS 17 (published in 2017). So whereas CMOS 16 shows the noun form “decision making” in its table, CMOS 17 has “decision-making.”
We hope this helps with your decision-making efforts! (As a preceding modifier, “decision-making” would be hyphenated even according to CMOS 16.)