Compound Words: One Single Word? Two Words? Hyphenated?


To hyphenate, or not to hyphenate: that is the question.


A compound word is a word composed of two or more words.


There are three types of compounds:

(1)  Closed compounds are words written as single words, such as “counteract”, “flashlight” and “overdose”

(2)Hyphenated compounds are words hyphenated, such as “self-control”, “passers-by” and “long-term”

(3)Open compounds are words written as separate words, such as “jump rope”, “post office” and “school bus”.



It is rather confusing whether a compound word is two words, a single word with no hyphenation, or a hyphenated word.


To check whether a compound noun is two words, one word, or hyphenated, you may need to look it up in the dictionary. Many compound words have been so frequently used that they are included in the dictionary as general vocabulary, such as “city hall”, “elementary school”, “counteract”, “deerskin”, “eyewitness” , “mother-in-law”, “all-inclusive”. These compound words are called permanent compounds.



If you can't find the word in the dictionary, there are some rules that you can follow.  


One way to decide if a hyphen is necessary is to see if the phrase might be ambiguous without it.


Compound Adjectives:

A compound adjective is a modifier of a noun. Compound adjectives do not always have hyphens.  They are hyphenated to avoid confusion. Generally, hyphenate between two or more adjectives when they come before a noun and act as a single idea.


For example:

(1)  Small appliance industry = A small industry producing appliances

(2)Small-appliance industry = An industry producing small appliances


Hyphenating the compound modifier in the second phrase clarifies that it is an industry producing small appliances. Without the hyphen, we might think that it is a small industry which produces appliances as in the first phrase.


However, they are not hyphenated if these modifying words come after the noun they modify.


For example:
Water-proof gloves.   

The gloves are water proof.
A high-valued product.   

The product is high valued.
A long-term solution.   

The solution is long term.
A two-year-old toddler.   

A toddler who is two year old cannot control his/her emotion.

A small-appliance industry.

An industry producing small appliances

This is a regulatory-mandated project.

This project is regulatory mandated.

They get a much-needed break from wok.

The break from work is much needed.


For more information about hyphenated compound adjectives, please refer to

For more information about compound words are formed, please refer to



Hyphenation is usually not used for adverb-adjective and noun-noun compound modifiers when ambiguity regarding meaning is not possible.


Compound Adverbs

Words are not hyphenated when combining an adverb (usually a word ending in "ly") and an adjective, because the adverb modifies the adjective rather than the subsequent noun.


For example:
An extremely long snake.

= A snake which is extremely long

A highly publicized actress.

= An actress who is highly publicized

A nationally known politician

= A politician who is nationally known

A heavily loaded container ship

= A container ship which is heavily loaded.


With the above phrases, confusion as to its meaning is unlikely since the adverb extremely clearly modifies the adjective long and not the noun snake.



Compound Verbs

Compound verbs are either hyphenated or appear as one word. If you do not find the compound verb in the dictionary, hyphenate it. Use a hyphen when a compound formed from two nouns is made into a verb.

For Example:
The owner handpicked the successor of his company yesterday.

We have technicians in house to troubleshoot any technical issues occurred after the conversion.

Due to poor economy, companies have to downsize to stay competitive.

It is time to upgrade your computer system.

It is absurd that the government tries to whitewash the scandals.

It is not easy to find someone to baby-sit our kids in such a short notice.

Don’t second-guess my intention!

He was court-martialed for insubordination.


My husband went test-driving a new car. (verb)

His test drive yesterday was quite pleasant. (noun)


He likes to ice-skate. (verb)

He has to buy a new pair of ice skates. (noun)


They booby-trapped the entire forest just to capture a bear. (verb)

The enemy falls into a booby trap. (noun)


I had to jump-start his car. (verb)

He asked me for a jump start. (noun)


We fast-tracked the project. (verb)

The project is on the fast track. (noun)


Phrases that have verb, noun, and adjective forms should appear as separate words when used as verbs and as one word (or hyphenated) when used as nouns or adjectives.


Please kiss and make up. (verb)


Don’t put too much makeup on your face. (noun)




You need to slow down while driving in the residential area. (verb)


The economic slowdown is depressing. (noun)




They broke inthe factories to steal the computers (verb)


The break-in last week costs the company five million dollars. (noun)




It looks like that the microwave will eventually break down. (verb)


There is a breakdown in the chain of command which impacts leadership effectiveness. (noun)




We have to make it a habit for the kids to clean up their room. (verb)


The cleanup process of the hostile takeover is pretty expensive (adjective)




It is difficult to follow up on so many targets, recommendations and commitments. (verb)


There is no time to complete all the follow-up activities. (adjective)



 Compound nouns

A compound noun is one consisting of two component nouns. In the past, these sorts of compounds were usually hyphenated, but the situation is different today. The tendency is now to write them as either one word or two separate words.


For Example:




Life Cycle


Written by Elisa English

On 09/14/12


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