Grammar Tip: Hyphenating Compound Adjectives

For most readers most of the time, whether a compound adjective is hyphenated or not isn’t going to affect comprehension, especially if the compound adjective is a common term such as “small business” in “small business loan” or “high school” in “high school teacher,” or if the text preceding the compound adjective prepares the reader for a specific interpretation, such as with leaving the compound adjective “transfer on death” unhyphenated in “The Texas Real Property Transfer on Death Act authorizes an individual to execute and record a transfer on death deed for . . .”).

But what if by “high school teacher” I mean a teacher under the influence of a drug? Sometimes your dictionary can come to the rescue. The dictionary I use shows “schoolteacher” (a closed compound noun) instead of “school teacher” (an open compound), so if I mean a teacher under the influence of a drug, I should use “high schoolteacher” (the adjective “high” modifying the closed compound noun “schoolteacher”) instead of “high school teacher” (the open compound noun “high school” serving as an adjective modifying “teacher”).

Still, if I don’t clarify in the text preceding “high schoolteacher” that I mean a teacher under the influence, it might leave some readers wondering if I simply made an amusing typo. Readers assume the norm, so a teacher of high school is usually inferred. But if I do mean an exception such as a teacher under the influence of a drug and I don’t clarify that before the reader gets to “high schoolteacher,” it’s better to state what I mean outright instead, for example, “schoolteacher under the influence of methamphetamine.”

I’d personally reserve hyphenating compound adjectives to only those instances where ambiguity exists without them or for those compound adjectives shown hyphenated in the dictionary I use, the latter simply for consistency.

For ambiguous instances hyphenation can clarify which of several possible meanings a writer intends. For example, “six inch thick boards” can have a number of meanings that hyphenation could narrow to the intended one:

• Six boards that are each one inch thick (“six inch-thick boards”);
• Multiple boards that are each six inches thick (“six-inch-thick boards”); or
• Multiple thick boards that are each six inches long (“six-inch thick boards,” though I’d probably rewrite that as “thick six-inch-long boards”).

Hyphenating compound adjectives can also prevent a misreading. For example, compare “I drive over the hill people downtown” with “I drive over-the-hill people downtown.” Both are insensitive, and the first is criminal—or at least risks briefly leading the reader down the wrong conceptual path.

Often, compound adjectives that benefit from hyphenation immediately before a noun don’t need to be hyphenated after the noun, because they no longer have that ambiguity. For instance, compare “out-of-state businesses” with “businesses out of state.” Some, however, should be hyphenated both before and after the noun, such as with “I’m over-the-hill” (if I’m referring to my age and not my location). Consult your dictionary.

If an adverb is part of a compound adjective, there’s usually no need to hyphenate it even before the noun. For example, there’s no need to hyphenate “highly decorated soldier” as “highly-decorated soldier,” because “highly” is an adverb, and adverbs can modify only adjectives, other adverbs, verbs, or entire sentences—but never nouns. The adverb “highly” therefore cannot modify “soldier” and must modify the “decorated” part. There’s no ambiguity about what modifies what, so there’s no need for the hyphen. What would a “highly soldier” even be?

Hyphenation in compound adjectives lends itself to other subtleties as well. One example is the suspended hyphen, which allows a writer to omit one or more words but still imply them, a type of elliptical construction we use in speech all the time.

Take, for example, the phrase “new and used clothing stores,” which can reasonably be interpreted two ways:

• Multiple stores, each of which sells both new clothing and used clothing (“new-and-used-clothing stores”), and
• Multiple stores, some of which sell only new clothing and others that sell only used clothing (“new- and used-clothing stores”).

The “new- and used-clothing stores” version uses a suspended hyphen, in this case implying “new-clothing stores and used-clothing stores.”

We should take care with hyphenation, though, or we might end up with phrases that are just as ambiguous as their unhyphenated counterparts. For example, “new-and-used clothing stores” literally means multiple clothing stores, each of which is somehow both a new store and a used store.

Most readers won’t interpret the phrase that way, because it’s nonsensical. It’s not clear what a “used” store would even be or how a store could be both new and “used” at the same time. Even so, readers would still be left wondering which of the two possible reasonable interpretations of “new and used clothing stores” the writer intended.

If you find yourself writing lengthy compound adjectives that seem overwrought with hyphenation, such as with “turn-of-the-twentieth-century doorknobs”—especially if they could be ambiguous without the hyphens, such as with “new-and-used-clothing stores”—rewriting is probably in order: “doorknobs from the turn of the twentieth century” or “stores that sell both new and used clothing.”