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Writing Tip: April 27, 2003
Compound Words: When to Hyphenate
A compound word is a combination of two or more words that function as a single
unit of meaning. There are three types of compounds: Those written as single
words, with no hyphenation, are called closed compounds--the word "flowerpot,"
for example. Hyphenated compounds, such as "merry-go-round" and "well-being,"
are the second type. Those in the third group, called open compounds, are written
as separate words--the nouns "school bus" and "decision making," for example.
Keep in mind that compounds can function as different parts of speech. In such
cases, the type of compound can change, too. "Carry over," for example, is an
open compound as a verb but a closed compound ("carryover") as a noun and an
--The money from that line item will carry over to next year's budget.
--The money we used for the trip was part of the carryover from last year's budget.
--Carryover funds can be used to cover a deficit.
When you don't know in which category a particular compound belongs, first try
looking it up in the dictionary. You will see there that some compounds are hyphenated
regardless of their function in a sentence. For example, "on-site" is a hyphenated
compound when it functions as an adjective or as an adverb: "The team conducted
on-site visits" and "The team conducted its review on-site."
The real confusion begins when the compound is not given in the dictionary. That
is, it is a compound that is being formed for a very specific situation. In such
cases, we have to rely on guidelines provided by the style manual to which we
adhere. Our style manual of choice, the Chicago Manual of Style, has a lengthy
section devoted to compound words--evidence that the rules are not simple.
Unfortunately, on this issue even the fairly straightforward rules about hyphens
leave some room for a writer's own judgment. Here is what the Texas Law Review
Manual of Style says about using the hyphen to create a compound word: "When
two or more words are combined to form a modifier immediately preceding a noun,
join the words by hyphens if doing so will significantly aid the reader in recognizing
the compound adjective" (20). The "if" clause in that sentence is the tricky
One way to decide if a hyphen is necessary is to see if the phrase might be ambiguous
without it. For example, "large-print paper" might be unclear written as "large
print paper" because the reader might combine "print" and "paper" as a single
idea rather than combining "large" and "print." Another such example is "English-language
learners." Without the hyphen, a reader might think we are talking about English
people who are learning any language rather than people who are learners of the
On the other hand, no one is going to be confused by the phrase "chocolate chip
cookies" or "Saturday morning cartoons." In other words, the open compounds (i.e.,
no hyphen) "chocolate chip" and "Saturday morning" are so well known that there
is no room for ambiguity. The open compound "high school" is so common, for another
example, that we would not hyphenate the phrase "high school students." We would,
however, hyphenate "high-risk" in the phrase "high-risk students."
The other time we must use hyphenation is to join a word to a past participle
to create a single adjective preceding the noun it modifies: "a well-intentioned
plan," for example, or "a horseshoe-shaped bar." Be aware, however, that we do
not hyphenate these same phrases when they FOLLOW the nouns they modify:
--This is a government-mandated program.
--The program is government mandated.
--She is a well-respected student.
--She is well respected as a teacher.
Another basic rule is that we never hyphenate compounds that are created with
"-ly" adverbs, even when they PRECEDE the nouns they modify: "a fully developed
plan," for example, or "a nationally certified teacher." Here are more examples:
--We sent in heavily fortified troops.
--The troops were heavily fortified.
--All newly employed nurses must be evaluated regularly.
--All the nurses on the eighth floor are newly employed.
--A beautifully designed room can be both relaxing and invigorating.
--The living room is beautifully designed.
For more information about hyphenating adjectives preceding nouns, see our previous
tip in the tip archive or in our book of writing tips on page 69.
Remember these two important points:
(1) We have three types of compounds: open compounds, closed compounds, and hyphenated compounds.
(2) Many of them are found in the dictionary and are not subject to our interpretation,
our judgment, or our whim. Start with your dictionary before applying any other
guidelines. (On-line dictionaries are easy to use. We favor Merriam-Webster's
New Collegiate Dictionary, 10th edition, available at http://www.m-w.com.
There is also the American Heritage Dictionary at http://www.bartleby.com/61/.)
Can you spot any errors in the use of compounds in the following sentences?
1. The war in Iraq has been a closely-monitored media event.
2. The Department of Transportation maintains rights-of-way alongside all roadways.
3. Follow up activities have been scheduled for June and July.
4. We must follow up on these changes.
5. Long term planning must be an essential goal of this company.
6. The committee centers all of its recommendations in performance based standards.
1. The war in Iraq has been a closely monitored media event. [No hyphen with
an "-ly" adverb, even though here it helps form a compound adjective preceding
2. correct [Webster's hyphenates "right-of-way" and the plural form "rights-of-way"
in all circumstances--even when the phrase is functioning as a noun, as in this
3. Follow-up activities have been scheduled for June and July.
5. Long-term planning must be an essential goal of this company.
6. The committee centers all of its recommendations in performance-based standards.
Copyright 2003 Get It Write
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