Grammar: Compound Word

Revised as of
2 Feb 2023

Compound words are a wide-ranging mishmash of rules covering words, numbers, proper nouns, adjectives, adverbs, directions, titles, and more. There’s also a hodgepodge of positioning and implication.

Writers will have to think as well, lol. I know, I know, more thinking on top of thinking . . . eek. The rules change depending on if it’s a Wednesday . . . well, not really. It only seems that way *more laughter*.

Getting serious, whether a compound of words is closed, open, temporary, permanent or other, if you question it, look it up in a dictionary. Use whichever dictionary you are already using as you write or edit.

In general, Chicago Manual of Style says to leave it as an open compound if the dictionary doesn’t tell you to use hyphens or to close it up. Of course, that general rule doesn’t apply when it comes to adjectival or temporary compound words!

Grammar Explanations is . . .

. . . an evolving list of the structural rules and principles that determines where words are placed in phrases or sentences as well as how the language is spoken. Sometimes I run across an example that helps explain better or another “also known as”. Heck, there’s always a better way to explain it, so if it makes quicker and/or better sense, I would appreciate suggestions and comments from anyone on an area of grammar with which you struggle or on which you can contribute more understanding.

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Compound Word
Definition: Two words joined together to create a new meaning. Compound words may be adjectives, adverbs, or nouns and how they are treated will change with which part of grammar they are and their location within a sentence. Post Contents: Open Compound Hyphenated Compound Closed Compound Permanent Compound Temporary Compound Compound Modifier (acts as an adjective) Rules for: -ly Adverb Capitalized Word Compass Points Numbers Modifier Position Compound Formed with Prefixes Proper Nouns & Proper Adjectives Suspended Compound (two or more compound words in a row) Also see: Compound Words in Formatting for rules on capitalization Combined Forms are very similar to the compound word; the “Combined Form” post is mostly a huh, so that’s what it is Noun Compounds for information on using nouns to modify nouns
Closed Compound	Rule: Spelled as a single word. The current trend is toward closed with CMOS using on line as an example of how it has progressed from on-line to online.
Return to top	birthrate citywide online notebook stepdaughter grandmother stepgrandson worldwide
	Rule: Compass points and directions are closed IF only two directions are combined. CAUTION: If three directions are combined, a hyphen must be used after the first direction.
	northeast southeast northwest southwest north-northeast east-southeast west-northwest
	CAUTION: If a from . . . to is implied, use an en dash.
	Phrase The Implied From . . . To The street runs east–west. The street runs from east to west. It’s a north–south race. The race runs from north to south.
Hyphenated Compound	Rule: Spelled with one or more hyphens with the intention of making the phrasing more readable and understandable and with two or more words.
Return to top	full-time kilowatt-hour mass-produced non-English-speaking non-achievement-oriented part-time
	Not Hyphenating Compound Words Leads to Confusion Compound Word The Implication fast decision making make a snap judgement fast decision-making make a decision soon much needed clothing They’ve got a lot of clothing. much-needed clothing This clothing is so essential.
	an abbreviation: pre-UCS trial
Open Compound	Rule: Spelled as two or more words OR using a comparative or superlative adjective that creates a short phrase with a focused meaning.
Return to top	Two or More Words Using a Comparative/Superlative high school better built house lowest common denominator more likely outcome Revolutionary War best laid plans
	Rule: Chemical terms do not use hyphens.
	Sodium hydroxide
Permanent Compounds	Rule: One that has been accepted into the general vocabulary and is found in a dictionary. It’s fairly safe to say that anytime a single letter is attached to a word, it’s with a hyphen.
Return to top	f-stop T-shirt browbeat e-mail pre-K copyeditor under-the-counter highlight waterfall anti-inflammatory matter-of-fact over-the-counter pre-engineered
Temporary Compounds	Rule: A new combination created for some specific, often one-time purpose. CMOS notes that these may eventually be accepted as permanent, but are not normally found in a dictionary.
Return to top	dictionary-wielding impeachment hound (I like this one!)
Compound Modifier	Definition: Hyphenate when two or more words in front of a noun act as one idea. Linking them together clarifies which word is playing which role. A.k.a., Phrasal adjective, one-thought adjective
Return to top	Consider What the Reader Will Understand
	Two Words How It Affects the Sentence The American made car. Sounds like someone doesn’t speak English very well. The American-made car. Instantly explains that this car is made in America. It’s recommended you not take down any load bearing walls when renovating. Oops, make sure that load over there isn’t holding up a wall. It’s recommended you not take down any load-bearing walls when renovating. Ohhh, you mean I shouldn’t take down any walls that are holding up a load. This is a low budget job. So, this is a budget job, and it’s low on the list of jobs to be done? This is a low-budget job. Ah, it’s a job we’re doing as cheaply as possible. First class decisions require clear headed thinking. First, any decisions we may for the class must be clear decisions. They must also be headed thinking. (I’m not sure what “headed” means.) First-class decisions require clear-headed thinking. Making the best decisions mean we need to be thinking clearly about them. He has a devil may care attitude. He has an attitude that the devil is going to be concerned about. (Ain’t that scary!) He has a devil-may-care attitude. He has a cheerful attitude.
	Position Within a Sentence is a Changer
	CAUTION: When using a compound modifier, pay attention to its position within the sentence. If it comes before the word being modified, use the hyphens. If it comes after the word being modified, do NOT hyphenate.
	Before the Modified Word After the Modified Word He is a well-respected man. That man is well respected. It’s a well-written story. That story is well written. This is a government-mandated program. This program is government mandated. I love that blue-green dress. That dress is a lovely blue green. Get the reddish-brown stone. You want the stone that is reddish brown? He’s a second-rate baseman. As a baseman, he’s second rate. Wow, we’re in a first-row seat! Wow, we’re sitting in the first row! It’s all-out war. She went all out to impress him.
	Exceptions to the position rule
	Always Hyphenate Examples ex- (noun that expresses a former state) Her ex-husband got fired. Tell him we hire ex-cons. She’s his ex-wife. self- It’s self-evident that she cheated. The instructions say it’s self-acting.
	Rule: Modifiers that end in -ly are never hyphenated.
	YES NO That was a badly punctuated sentence. That was a badly-punctuated sentence. It was a fully developed plan. It was a fully-developed plan. She’s a a nationally recognized teacher. She’s a a nationally-recognized teacher. We sent in heavily fortified troops. We sent in heavily-fortified troops.
	Rule: Proper nouns and proper adjectives are never hyphenated as they are already correct.
	YES NO The South American rain forest is home to hundreds of species of hummingbirds. The South-American rain forest is home to hundreds of species of hummingbirds.
	Rule: When numbers or units of measure are used as an adjective, hyphenate them.
	two-seater aircraft thirty-pound weakling 4-bedroom house five- to ten-minute intervals nineteenth-century painter 12-inch rule pre-1998 three-week course
	Exceptions to the “hyphenate numbers” rule.
	Percent Always spell percent out in text Never use % Never hyphenate a 15 percent raise
Compounds with Prefixes	Rule: While there are some exceptions, compounds created by the addition of a prefix are not hyphenated. No, this is not a complete list of prefixes. Prefixes with a dotted underline are also combined forms.
Return to top	ante- antecedent anteroom antechamber mid- midsection midtown midway anti- antimanagement antismoking antisocial mini- minibike minicab minicomputer bi- binomial bimonthly biannual mis- misinformed mismanage misprint bio- biochemistry biography multi- multicultural multiplex co- coordinate copayment coworker neo- neonate neoromantic neoimpressionists counter- counterbalance counterclockwise counterpoint non- nonaffiliated nonaggression nonviolent de- decompress deduct descend out- outfight outmoded outpost dis- disbar dislike disgruntled over- overanxious overemphasize overplay extra- extraordinary extracurricular extraterritorial post- postoperative posttraumatic postwar hyper hyperactive hyperlink hyperthyroid pre- precaution precede prejudge in- inanimate inpatient intolerant pseudo- pseudointellectual psuedonym pseudoscience infra- infrastructure re- reactivate revert reunify inter- interactive interagency interrelated semi- semicircular semiconductor semidarkness intra- intramural intrauterine socio- socioeconomic sociolinguistics macro- macroeconomics macroevolution macronutrient sub- subalpine submarine subpar mega- megabyte megahertz megalith super- superman superstructure supertanker meta- metacarpus metamorphosis metaphysical trans- transatlantic transcontinental translate micro- microcircuit microdot microeconomics un- uninfected unnatural under- undercover underdeveloped undernourished
	Exceptions include:
	Rule: Use a hyphen if the second element is capitalized or a number . . .
	anti-Semitic post-Freudian pre-Civil War ten-book series
	Rule: If a hyphen is needed to avoid confusion between words that would conflict.
	co-op a cooperative society coop a building for chickens re-form cause to form again reform make changes in something to improve it re-pair pair up again repair fix un-ionized not ionized unionized become members of a union
	Rule: Use a hyphen if a vowel or consonant would be repeated so as to avoid confusion.
	Yes No anti-intellectual antiintellectual semi-independent semiindependent ball-like balllike Exceptions to this rule include: reestablish reedit
	Rule: Use a hyphen if the compound word would be difficult to read without a hyphen.
	Yes No pro-life prolife pro-choice prochoice co-edited coedited
Suspended Compound	Definition: Rather than repeat the same final term in a list, the completion of the compound words is deferred until the last item in the list while allowing the hyphen to act as a placeholder. A.k.a., combined noun compounds
	second-, third-, and fourth-grade teachers full- and part-time employees 1-, 2-, and 3-year-old children under- and overdeveloped nations get together

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C’mon, get it out of your system, bitch, whine, moan . . . which words are your pet peeves? Also, please note that I try to be as accurate as I can, but mistakes happen or I miss something. Email me if you find errors, so I can fix them . . . and we’ll all benefit!

Satisfy your curiosity about other Grammar Explanations by exploring its homepage or more generally explore the index of self-editing posts. You may also want to explore Book Layout & Formatting Ideas, Formatting Tips, Grammar Explanations, Linguistics, Publishing Tips, the Properly Punctuated, Word Confusions, Writing Ideas and Resources, and Working Your Website.

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Resources for Compound Word

Some of these links may be affiliate links, and I will earn a small percentage, if you should buy it. It does not affect the price you pay.

Chicago Manual of Style, 6.78, 7.83, 7.84, 7.85. 17th ed. University of Chicago Press: 2017. <https://amzn.to/40ALORI>. Hardcover.

Grammarly Handbook: Hyphen With Compound Modifiers

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