Q: In your “Compound fractures” post from 2012, you discuss hyphenating “potentially confusing compounds.” Shouldn’t that be “potentially-confusing”? I’m not being snarky, mind you, just trying to understand.
A: The use of hyphens in compounds is pretty straightforward—except when it isn’t.
One of the many exceptions to the conventions of hyphenation is that when an adjective is modified by an “-ly” adverb, the compound doesn’t get a hyphen.
Pat uses these examples in her grammar and usage book Woe Is I: “That’s a radically different haircut. It gives you an entirely new look.”
We’ve written before about when to hyphenate compound modifiers, but a little repetition never hurts.
You’re probably familiar with the general practice.
Two-word descriptions are hyphenated before a noun (“powder-blue suit,” “dark-haired toddler,” “well-done steak”). But if the description comes after the noun, no hyphen is used (“a suit of powder blue,” “a toddler who’s dark haired,” “a steak well done”).
Now for some more exceptions.
Compound modifiers in which one of the words is “very,” “most,” “least,” or “less” (as in “most pleasing tune”) don’t have hyphens.
Some prefixes usually take hyphens (as in “self-effacing manner,” “quasi-official position”). Others sometimes do and sometimes don’t (“pre-,” “re-,” “ultra-,” “anti-”).
However, the hyphenation of prefixes is very fluid, and authorities may differ. A prefix that’s hyphenated in one dictionary or style guide may not be in another. If in doubt, check your dictionary or style manual.
In case you’d like a short refresher course on hyphens, we wrote in April 2013 about omitting part of a hyphenated term (as in “full- and part-time job”); in July 2012 about hyphens in dimensions (like “five-foot-six woman”); and in January 2012 about when to hyphenate a term like “African American.”
You can find others by putting “hyphen” in the search box on our blog.
from Grammarphobia http://www.grammarphobia.com/blog/2017/04/compounds-2.html