Compound adjectives are combinations of two or more words that function together to describe a noun. They are commonly used in English to add clarity and detail, especially before the noun they modify. Most are written with hyphens. In this guide, you’ll learn what compound adjectives in English are, how to form them, when to use hyphens, and see plenty of grammar rules, structures, and examples.
What Is a Compound Adjective?
A compound adjective is a combination of two or more words that function together as a single descriptive unit to modify a noun. These combinations give more precise information than a single adjective alone and typically appear before the noun they describe.
They often answer questions like What kind?, Which one?, or How many?, and are commonly used to improve clarity in both writing and speech.
Examples:
- a well-known singer
- a two-door car
- a five-year-old child
Compound adjectives are usually hyphenated when placed before a noun to show that the words act as one idea and to avoid confusion (e.g., She lives in a high-rise apartment).
Structure of Compound Adjectives
Compound adjectives are formed by combining two or more words that act as a single adjective before a noun. The structure depends on the type of words used. Below is a full guide to the most common patterns:
| Structure | Example |
|---|---|
| Adjective + Participle | old-fashioned, high-pitched |
| Noun + Participle | hand-made, sun-dried |
| Adverb + Participle | well-known, highly-respected |
| Adjective + Noun | full-length, short-term |
| Noun + Noun | world-class, ice-cold |
| Number + Noun | two-hour, five-story |
| Noun + Adjective | snow-white, coal-black |
| Preposition + Noun | over-the-top, under-the-radar |
| Number + Past Participle | well-trained, high-priced |
Note: These structures are typically hyphenated when placed before a noun. If they come after the noun, the hyphen is usually not used (e.g., The singer is well known).
Types of Compound Adjective Structures
Compound adjectives are typically formed by joining two words that together describe a noun. Below are the most common and useful structural patterns you’ll see in English:
1. Adjective + Past Participle
Used to describe characteristics or conditions in a precise way.
- old-fashioned: She wore an old-fashioned dress to the party.
- short-lived: Their short-lived success didn’t last beyond the first year.
- high-pitched: The child screamed in a high-pitched voice.
2. Adjective + Present Participle
Often describes someone or something’s ongoing quality or behavior.
- good-looking: He’s a good-looking man with a friendly smile.
- easy-going: She has an easy-going attitude that puts people at ease.
- long-lasting: This phone comes with a long-lasting battery.
3. Noun + Past Participle
Commonly used in food, technology, and everyday items.
- sun-dried: I added sun-dried tomatoes to the pasta.
- home-cooked: There’s nothing better than a home-cooked meal.
- machine-generated: The system processes machine-generated data instantly.
4. Noun + Present Participle
Emphasizes what the noun is doing or causing actively.
- record-breaking: The record-breaking athlete won three gold medals.
- time-consuming: Filling out that form was a time-consuming task.
- eye-catching: The poster had an eye-catching design.
5. Adverb + Past Participle
Adds detail about the degree or manner of the adjective.
- well-written: She submitted a well-written article for the magazine.
- highly-trained: We hired a highly-trained staff for the project.
- poorly-maintained: Drivers complained about the poorly-maintained road.
6. Number + Noun
Frequently used to express quantity, measurements, or age. Always hyphenated before the noun.
- five-year: The government launched a five-year plan.
- ten-minute: Let’s take a ten-minute break.
- two-hour: It’s a two-hour drive to the city.
7. Noun + Noun
The first noun modifies the second noun and acts as a single descriptive unit.
world-class: He’s a world-class chef known for creative dishes.
ice-cold: She handed me an ice-cold drink.
data-driven: We implemented a data-driven solution to the problem.
8. Noun + Adjective
Less common, but used for poetic or descriptive effect.
- snow-white: The puppy had soft, snow-white fur.
- coal-black: She stared at me with coal-black eyes.
- stone-hard: He fell on the stone-hard ground.
Hyphenation Rules for Compound Adjectives
Compound adjectives are usually hyphenated when they appear before a noun. The hyphen links the words together to show they function as a single unit modifying the noun. The use or omission of a hyphen depends on the position, structure, and word types involved.
1. Hyphenate Before a Noun
When two or more words function as one adjective and appear before a noun, they must be hyphenated to avoid misreading.
Examples:
- a well-written article
- a part-time worker
- a fast-moving train
2. Don’t Hyphenate After a Noun
When the same combination of words appears after the noun, the hyphen is generally omitted, as the grammatical relationship is clear without it.
Examples:
- The article is well written.
- His schedule is full time.
- That engine is high speed.
3. Hyphenate Number + Noun Before a Noun
When a cardinal number (e.g., two, five) or ordinal number (e.g., first, third) is used with a noun to modify another noun, the entire phrase should be hyphenated.
Examples:
- a five-year-old boy
- a ten-minute speech
- a three-story building
4. Hyphenate Adjective/Noun + Participle
When an adjective, noun, or adverb is combined with a present participle (-ing) or past participle (-ed) to form a compound adjective, hyphenation is required before the noun.
Examples:
- a well-behaved child
- a sun-dried tomato
- an easy-going manner
These are not hyphenated when placed after the noun:
- The tomato is sun dried.
- His manner is easy going.
5. No Hyphen with -ly Adverbs
Adverbs ending in -ly are not hyphenated when they modify adjectives, even before a noun. The adverb clearly functions separately, so no hyphen is needed.
Examples:
- a highly skilled engineer
- a poorly maintained building
- a newly published book
6. Use Hyphens to Prevent Ambiguity
If a phrase could be misread or has multiple interpretations without a hyphen, it should be hyphenated for clarity, even if not strictly required.
Examples:
- a small-animal hospital (not a hospital that is small, but one for small animals)
- a man-eating shark (not a man who is eating a shark)
7. No Hyphen in Predicative Position
When compound adjectives follow the verb (be, seem, look, etc.), they are not hyphenated unless they are part of a fixed expression or used attributively.
Examples:
- The design is user friendly.
- This software is well known.
8. Hyphenate with Proper Nouns or Capitalization
If a compound adjective includes a proper noun or a capitalized term, the hyphen is still used.
Examples:
- a New-York-based company
- a Pre-Raphaelite-style painting
9. No Hyphen with “Very” or Non-ly Adverbs
Hyphenation is not used when the first word is very or an adverb like quite, rather, or too.
Examples:
- a very important decision
- a rather tired expression
Compound Adjectives with Numbers
Compound adjectives with numbers are used to describe age, time, length, quantity, and similar measures. When placed before a noun, they always include a hyphen and the noun remains singular.
Examples:
- a five-minute break
- a six-foot tall man
- a ten-dollar bill
- a twenty-page report
Compound Adjectives with Adverbs
Adverbs, especially those not ending in -ly, often combine with adjectives or participles to form compound adjectives before a noun. Use a hyphen if the adverb does not end in -ly (e.g. well-known artist), but do not use a hyphen if it does end in -ly (e.g. carefully written essay).
Examples with hyphen:
- a well-known artist
- a highly-paid employee
- a fast-moving vehicle
Examples without hyphen:
- a carefully written essay
- a beautifully painted mural
- a recently discovered island
Compound Adjectives with Superlatives
Compound adjectives with superlatives are used to express the highest or most extreme degree of a quality. They typically begin with a superlative word such as best, worst, most, or least, followed by a noun, adjective, or participle to form a strong, descriptive unit.
Examples:
- a best-selling author
- the worst-case scenario
- a most-loved celebrity
- a least-expected result
