Compound Noun

Introduction to Compound Nouns

A Compound Noun is the combination of two or more existing nouns or other parts of speech used together to express a single meaning. They are part of one unit and have become a set phrase.

Compound nouns usually consist of two nouns such as foot + ball. They vary in form; some are closed, some are open, and some are hyphenated.

The following are some examples of compound nouns:

Closed FormsOpen FormsHyphenated Forms
airpackair bagback–pedaling
carjackingbomb squardby–product
deathtrapcase studydo–gooder
eyewitnessdeath rateno–brainer
fingerprintflash floodplea–bargain
pickpocketshock waveself–defense
wheelchairstreet smartsstretcher–bearer

In compound nouns, the first word is usually stressed, and the two words are said together, with no pausing in between the words.

Forms of Compound Nouns

Some compound nouns are a combination of a noun and a present participle (the –ing form of a verb), written as two words. However, some are written either as open or closed compounds, while others are separated by a hyphen.

Open FormsClosed FormsHyphenated Forms
blood poisoningfirefightingcrime–fighting
decision makinglifesavingname–calling
report writingshopliftingwife–beating
drug testingsafecrackingwhistle–blowing
problem solvingtroubleshootingstreet–fighting
Important Hints 

If you are uncertain as to which choice to adopt, consult your dictionary. And if the dictionary happens to show two options, for example, baby–sitting and babysitting, adopt the option that suits your style.

If however, the particular compound is not listed in the dictionary and you can’t find a similar compound to compare to, you may resolve to write the compound as two words.

Compound nouns which are a combination of verb and adverb are usually written closed or hyphenated. Several of these forms can be written both ways. These particular compounds require extra effort to remember the appropriate pattern of writing them. Different dictionaries, we have observed, show different spellings, as even grammar experts tend to disagree in this particular area.

cover–upbackupblackoutdrive–by
show–offflareuplineupsign–out
flashbacklockdownsize–upbreakout
pileupspin–outcheckoutget–together
standbycleanuphangoutrunaway
cop–outhideawayrunoffwashdown
shootoutwalk–throughripofffollow–up
wind–upbreak–inknockdown
Important Hints  

Note that regardless of how these combination of verb and adverb compound nouns are spelled, these same expressions are written as two separate words when serving as verb phrases.

Used as Noun

  • The CDC is investigating a possible Ebola breakout in Reston.
  • I noticed it during my initial size–up.

Used as Verb Phrase

  • Break out the Level A chemical suits.
  • Let me size up the situation.

Sometimes a lone letter is combined with a word to express one meaning. When this happens, a hyphen is usually used to separate the two. However, when the connection between the two is clear without a hyphen, the compound may be written in open form.

A–Framee–mail/E–mailH–bombI–beam
O–ringT cellT–shirtU bolt
U-turnX chromosomeX–ratedy–axis
x–rayx rayX rayX–ray

Some phrases serving as compound nouns are usually hyphenated:

a free–for–alla good–for–nothing
a know–it–allmake–believe
hide–and–seeka jack–for&all–trade
a pick–me–upa stick–in–the–mud
a johnny–come–latelystick–to–it–iveness

Most compound nouns formed from repeated or rhyming words are usually hyphenated:

boo–boogoody–goodyhanky–panky
hocus–pocusnitty-grittyno–no
pooper–scooperrazzle–dazzlewalkie–talkie

This particular form of compound nouns consists of a possessive noun followed by another noun and are usually written in open form. However, some are written in hyphenated form. A few of this form take the closed form (and written without the apostrophe).

fool's goldhornet's nestbird's–eye
ratsbanewolfsbanecrow's–feet

And the following, which can be written either open or closed:

OpenClosed
men's wearwomen's wearmenswearwomenswear

Proper nouns in this form are often written open:

Central AmericanFrench Canadian
Native AmericanMiddle East

The compound is written hyphenated if it contains a prefix or combining form in place of a full word:

Afro–AmericanAnglo–Saxon

Family titles containing great or in–law are always separated by a hyphen:

great–grandmothermother–in–law
great–grandanimalfather–in–law

Job titles containing man, men, woman, or women are usually written closed. However, while it is acceptable to use these terms when referring to a specific person, it is a preferable practice to replace these titles with terms that do not suggest gender specification:

Gender SpecificNon Gender Specific
firemanfirefighter
policewomanpolice officer
foremensupervisors
saleswomansalesperson

Civil and military titles are typically not hyphenated:

attorney generalchief of staff
lieutenant governorchief of police
sergeant at armscommander in chief
some with exceptions:
ambassador–at–largeattorney–at–law

When it comes to compound titles containing the prefix ex– and the suffix –elect, and forms containing vice; hyphens are usually applied to separate the compounds:

ex–presidentpresident–elect
vice–chairmanvice–chancellor
Either hyphens or slashes may be applied to indicate combined titles:
owner–operatorauthor–publisher
firefighter–engineersecretary–treasurer

Guidelines to follow

1.  While a number of compound nouns are hyphenated in form, the majority are either closed or open. Some compound nouns are often written closed when they are short, when they are commonly used, and when the accent is stressed on the first syllable:

airwaybloodstreamdeadlinefirebug
footprintgraveyardgunfighthealthcare
hotheadpacemakershortcutsmallpox

2.  Short compound nouns tend to be written open when the accent is not heavily stressed on the first syllable.

alarm boxblood cellblue devildead time
fire truckhot spotleg woundred alert
short circuittime bombwaste productyellow fever

3.  Similarly, longer compound nouns, are usually written open.

automatic weaponchemical reactiondisaster planningdrug interruption
internal bleedingmalicious mischiefprobable causenitroglycerin tablet
respiratory distresssprinkler systemunlawful entrywater damage
Important Hint 

Note that some compound nouns can be written in more than one way: (high-rise, high rise, and highrise). In such a case, we recommend you implement the style that suits you and be consistent with it.