A compound adjective involves two or more words working together to modify a noun. In the phrase “hot-water bottle,” for example, “hot” describes the temperature of the water, and together they describe the type of bottle in question. The hyphen removes any possible ambiguity; after all, a hot-water bottle is different from, say, a regular bottle of water that’s been sitting in a hot car all day.
The three most commonly used types of compound adjectives are composed of either two adjectives, an adverb and an adjective, or a multiple-word phrase. Let’s look at some examples:
- Adjective+Adjective: long-term substitute, hot pink blouse, open-minded governor
- Adverb+Adjective: well-stocked liquor cabinet, brightly lit cell, fast-paced drama
- Multiple-Word Phrase: all-too-common mistake, six-year-old collie, “get out of jail free” card
An easy test for determining if you’ve got a compound adjective on your hands is to say each modifier separately with its noun. If it sounds odd or ambiguous, then it’s probably a compound adjective. If you break down our first example, “long-term substitute” into “long substitute” and “term substitute,” it loses its meaning. That’s because “long” modifies “term,” not “substitute.” Compare this to “her big blue eyes.” Her eyes are both big and blue, and therefore “big blue” is not a compound adjective.
Once you’ve identified a compound adjective, you have to determine if it should be hyphenated. Like most of the irritatingly vague rules of English grammar, the answer is, “It depends.” If the compound adjective comes after the noun it modifies, it is not hyphenated. For example, the sentence “He acts like a ten year old” doesn’t need hyphenation, but “The ten-year-old boy would not stop kicking the back of my seat” does.
You can have more than one compound adjective in a series, such as “long-term, live-in lover.” If you have a series of two compound adjectives that share the same root, such as “long-term” and “short-term,” you should use suspended hyphens. For example, “Eight- and ten-year-old girls like My Little Pony, but so do twenty- and thirty-year-old men.” Suspended hyphens save us the trouble of repeating the shared root (in the example above, “year-old”).
Compound adjectives that appear before the nouns they modify follow an arcane set of rules. Whether you use a hyphen, or not, depends more on convention and taste than on logic. Compound adjectives of measurement and age (six-foot monitor lizard, twenty-year-old swimmer) will always be hyphenated, but colors usually aren’t (bright yellow soda, dark blue eyes). Adverbs that end in –ly don’t get hyphens (deeply puzzling riddle, dimly illuminated vault), but other adverbs do (well-read author).
Shorter phrases are usually hyphenated (all-too-common mistake), but longer phrases (“get out of jail free” card) are often placed in quotation marks. Foreign phrases, such as Latin, are usually done in italics (her in absentia vote).
If your head is spinning, never fear; there is an easy trick to help you. Rather than memorizing every single exception to the rule, simply read the sentence out loud. If there is any potential for confusion, use a hyphen. It’s doubtful that a reader would be confused by the sentence “Check out that funny looking sloth.” While you could conceivably have a “funny sloth,” you wouldn’t have a “looking sloth.” A hyphen is therefore unnecessary.
Sometimes, however, there can be ambiguity. Consider the Red Hot Chili Peppers. With its current lack of a hyphen, the band name could be read two ways: chili peppers that are red hot, or chili peppers that are both spicy and the color red. Lead singer Anthony Keidis was unavailable for comment, so we may never know the correct answer.
When in doubt, use a hyphen. After all, there is a difference between “a man-eating shark” and “a man eating shark.”
How about you? Any questions about hyphen use? Any funny examples? Ask/post in comments.
About the Author
A self-proclaimed word nerd, Allison VanNest works with Grammarly to help perfect written English. Connect with Allie, the Grammarly team, and nearly 690,000 Grammarly Facebook fans at www.facebook.com/grammarly.
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