Sometimes when more than one adjective is used to modify a noun, the adjectives must be hyphenated to make the meaning clear. But lets start with a case where hyphenation is unnecessary.
- dangerous bacterial infection
- sprawling suburban plan
- polite postal workers
Dangerous, sprawling, and polite are adjectives, and infection, plan, and worker are nouns. The words in the middle are also adjectives, but in these uses they combine with the final nouns to create a compound nouns that express a single concept. In each case, the first word modifies the next two. Dangerous modifies bacterial infection. Whether or not postal workers are polite is beyond the scope of this article.
But what about these?
- gay rights advocate
- minor league umpire
- live action directing
These first words are adjectives and the third ones are nouns. However, the middle words are nouns that combine not with the following nouns, but with the adjectives that precede them. These are compound adjectives. The first refers to an advocate for gay rights, not a general advocate for rights who happens to be gay. It’s the league that’s minor, not the umpire. So we need to clarify the meaning and indicate proper compounding by connecting the first two words: gay-rights advocate, minor-league umpire, live-action directing.
We can also have two or more adjectives modifying a final noun:
- short black hair
- sweet young lady
- stout little man
None of these combinations need to be hyphenated because their meanings are clear. The hair is short and black; the lady is both young and sweet; the man is little as well as stout.
Hyphenating multiple adjectives
But what about the following?
- exported vegetable products
- offensive language patterns
- stone carving blade
Are the middle words supposed to combine with their preceding adjectives, or with the final nouns? There’s a difference between products made of exported vegetables and vegetable products that are exported. Are the patterns studied those of offensive language? Or are the language patterns themselves offensive? Is the blade meant for carving stone, or is the carving blade made of stone? You must make the meaning clear by correctly combining the words with a hyphen: stone-carving blade, etc.
Five week old kittens are beginning to get frisky. Are there five kittens only a week old? (Five week-old kittens…) Or an indeterminate number of kittens that are five weeks old? (Five-week-old kittens…)
To indicate how multiple adjectives modify a noun, you must clarify meaning with commas or hyphens. For instance, in the garden you see a red striped lizard and post about it on Facebook. Is it a red lizard that is striped (red, striped lizard), or a lizard with red stripes (red-striped lizard)?
Hyphenate to prevent confusion
You must also hyphenate compound adjectives that precede a noun if, unhyphenated, would lead to ambiguity or confusion. The new student questionnaires will be distributed on the first day of school. Are the questionnaires for new, incoming students? (The new-student questionnaires…) Or are the student questionnaires changed from the old ones? (The new student-questionnaires…)
Hyphenating adverbial compounds
When verbs are modified with adverbs that end in “-ly,” the compound should not be hyphenated.
- Incorrect: The abattoir was run by a highly-skilled team of butchers.
- Correct: The abattoir was run by a highly skilled team of butchers.
- Incorrect: Add a pinch of freshly-chopped basil.
- Correct: Add a pinch of freshly chopped basil.
However, the exception is that, if an “-ly” adverb is used with a preceding compound adjective that has at least two other components, use a hyphen: She rattled off what sounded like a quickly-made-up story. Another exception is to drop hyphens when the same words follow the noun being modified: She rattled off a story that sounded like it was quickly made up.
When a non-“-ly” adverb is used in a compound adjective preceding a noun it modifies, link them with a hyphen: The well-written novel is a bestseller. Drop the hyphen if the modifying words come after the noun: The bestselling novel is well written.
The suspense is hyphenating me
A final use for hyphens is as a shortcut to abbreviate a repeated base word that uses different modifiers. Confused? An example should help.
At times she both undercompensated and overcompensated for her actions. Two fat, repeated words could be trimmed down like this: At times she both under- and overcompensated for her actions.
A suspension hyphen lets readers know that there’s something intentionally missing. The suspension hyphen can also be used to precede a repeated compound word: The secretary took minutes of the Day-1 and -2 proceedings.
Are we done yet?
There are a few more rules and exceptions, but frankly, I’m exhausted. So we’re done with hyphens, okay?
Next up, more about problematic participles and misplaced modifiers. Nothing at all about alliteration.
Source: Anne Stilman’s Grammatically Correct: The Writer’s Essential Guide to Punctuation, Spelling, and Grammar (Writer’s Digest Books, 1997).
What about when an -ly adverb is followed by two (or more) modifiers, as in this example: “empirically grounded learning module”? The meaning seems clear enough without a hyphen after “empirically” but I can’t find definitive guidance online for this situation.
Empirically modifies grounded, and learning modifies module. If anything could be hyphenated, George, it would be learning-module. But that seems a bit clunky. You’re first take is right; the meaning is clear without any hyphens.