In English, some nouns are made by joining two or more words together to create a single idea. These are called compound nouns. Words like toothbrush, ice cream, and mother-in-law are all compound nouns. Each one combines smaller words into a single unit that names a person, place, thing, or idea.
What Is a Compound Noun?
A compound noun is a noun made by joining two or more words that work together to name a single thing, person, place, or idea. The combined words form one unit of meaning.
Even though a compound noun may contain more than one word, it functions just like any other noun—it can be a subject, object, or part of a phrase.
Examples:
- toothbrush
- mother-in-law
- ice cream
- bus stop
- laptop
Each of these examples represents one specific thing, even though they may contain multiple words.
Sentence Example:
- She packed a new toothbrush in her bag.
- We stopped at the bus stop after lunch.
Characteristics of Compound Nouns
Compound nouns have unique features that make them easy to recognize and use correctly. Here’s what sets them apart:
They combine two or more words into one noun
Each part of a compound noun works together to express a single idea. The meaning is often different from the individual words on their own.
Example: greenhouse = a glass building for plants (not a green-colored house)
They can be written in three forms
- Closed (solid): no space (notebook, bedroom)
- Hyphenated: joined by hyphens (mother-in-law, editor-in-chief)
- Open (spaced): written as separate words (ice cream, bus stop)
They follow standard noun rules
Like other nouns, compound nouns can be:
- countable or uncountable
- singular or plural
- used as subjects, objects, or complements
The main word usually comes last
In most compound nouns, the last word tells you what the item is.
Examples:
- police officer → type of officer
- coffee table → type of table
Types of Compound Nouns
Compound nouns can be classified based on how they are written.
1. Closed or Solid Compound Nouns
These are written as a single word without spaces or hyphens.
Examples:
- toothbrush
- laptop
- football
2. Hyphenated Compound Nouns
Hyphenated compound nouns use a hyphen to connect the words. This format is common with family relationships, job titles, or when the meaning might be unclear without hyphens.
Examples:
- mother-in-law
- editor-in-chief
- check-in
3. Open or Spaced Compound Nouns
Spaced compound nouns are written as two separate words, but they function as a single noun.
Examples:
- ice cream
- bus stop
- post office
Formation of Compound Nouns
Compound nouns are formed by combining words from different parts of speech. The structure and meaning depend on how the words interact. Below are the most common formation patterns:
1. Noun + Noun
Two nouns combine to create a new, more specific noun.
Examples:
- classroom (a room for classes)
- toothbrush (a brush for teeth)
2. Noun + Verb
A noun followed by a verb that relates to the noun’s function or action.
Examples:
- haircut (the act of cutting hair)
- rainfall (rain that falls)
3. Noun + Adjective
Less common, but sometimes used to describe a condition or characteristic related to the noun.
Examples:
- court-martial (a military court—here the adjective qualifies the court)
- sun-dried (dried by the sun — often used in compound adjectives like sun-dried tomatoes)
4. Noun + Prepositional Phrase
A compound made of a noun followed by a prepositional phrase (phrase starting with a preposition). These are typically hyphenated and refer to specific roles or relationships.
Examples:
- mother-in-law
- commander-in-chief
5. Verb + Noun
The verb describes an action related to the noun.
Examples:
- swimming pool (a pool for swimming)
- washing machine (a machine used for washing)
6. Preposition + Noun
The preposition modifies the meaning of the noun.
Examples:
- overcoat (a coat worn over clothes)
- underground (beneath the ground)
7. Verb + Preposition
These combinations can describe direction or purpose.
Examples:
- take-off (the action of lifting off — often used in aviation)
- check-out (as in hotel checkout or a checkout counter)
8. Adjective + Noun
The adjective modifies the noun to create a new concept.
Examples:
- blackboard (a board that is black)
- greenhouse (a glass house for growing plants)
Compound Noun Examples in Sentences
- I bought a new notebook for class.
- The sunflower bloomed early this year.
- Her mother-in-law is staying with them this weekend.
- He’s the editor-in-chief of the magazine.
- We met at the bus stop near the library.
- Please bring the ice cream to the table.
Compound Noun vs. Simple Noun
The difference between compound nouns and simple nouns is that a compound noun is made up of two or more words, while a simple noun consists of just one word that stands alone.
| Simple Noun | Compound Noun |
|---|---|
| room | classroom |
| light | flashlight |
| rain | raincoat |
| board | whiteboard |
How to Identify Compound Nouns
Here are some simple tips to help you spot compound nouns:
Look for two or more words acting as one noun
If a pair (or group) of words comes together to name a single thing, person, place, or idea—they likely form a compound noun.
Example: bus stop → a specific place, not two separate ideas (bus + stop)
See if the meaning changes when the words are combined
The meaning of a compound noun is usually more specific than the individual words alone.
Example: book + case = bookcase (a piece of furniture, not just a case or a book)
Test the noun’s role in a sentence
If the group of words works together as a subject, object, or complement, it’s likely functioning as one noun.
Example: The washing machine is broken.
Here, washing machine is the subject and acts as a single unit.
Check spelling patterns
Compound nouns come in three forms:
- Closed: notebook
- Hyphenated: mother-in-law
- Open: swimming pool
If you see a combination like this functioning as one idea, it’s a compound noun.
FAQs About Compound Nouns
Can compound nouns be pluralized?
Yes, but the plural form usually depends on the main noun in the compound.
toothbrush → toothbrushes
mother-in-law → mothers-in-law
bus stop → bus stops
Always pluralize the most important word in the phrase, not just the last one.
How do I know when to hyphenate a compound noun?
There’s no single rule. Some compound nouns are always hyphenated (mother-in-law), while others are not. The best approach is to check a reliable dictionary if you’re unsure.
Are all compound nouns made of two nouns?
No. While many compound nouns combine two nouns (bookcase, toothpaste), others use adjectives, verbs, or prepositions.
adjective + noun: blackboard
verb + noun: swimming pool
noun + preposition + noun: commander-in-chief
Do compound nouns always have a clear meaning?
Not always. Some are straightforward (bedroom = a room with a bed), while others are more idiomatic (butterfly is not a fly made of butter). In many cases, the meaning must be learned as a whole.