“Sunrise” = “sun” + “rise”
In English grammar, compound nouns are combinations of two or more words that function as a single noun. In addition, these nouns can be open, closed, or hyphenated. They’re a common feature of the language and can be formed in different ways depending on the words involved and how they’re combined. English uses compounding to create concise, specific terms without needing long phrases. It’s a flexible, efficient way to expand vocabulary—think “smartphone” or “cloud storage” as modern examples.
What compound nouns are
- A compound noun refers to a person, place, thing, or idea that is made up of two or more words.
- These words can be formed with adjectives, other nouns, prepositions, and verbs. Here are the common formats:
- Adjective plus noun: “greenhouse” (green + house)
- Noun plus noun: “basketball” (basket + ball)
- Noun plus verb: “haircut” (hair + cut)
- Preposition plus noun: “underground” (under + ground)
- Verb plus noun: “swimming pool” (swimming + pool)
How they are formed
Compound nouns can be formed in three main ways. They can be closed, open, or hyphenated.
- Closed or solid compound nouns
- These are written as a single word.
- Examples: “sunflower,” “bedroom,” “toothpaste.”
- Hyphenated compound nouns
- These are connected by a hyphen (-).
- Sometimes more than two words are involved, like “sister-in-law” or “jack-of-all-trades,” though these are less common and often hyphenated for clarity.
- More examples: “mother-in-law,” “check-in,” “passer-by.”
- Open or spaced compound nouns
- These consist of two or more separate words.
- Examples: “swimming pool,” “bus stop,” “post office.”
Rules and flexibility of use
- Pluralization: Usually, the main noun (the “head” of the compound) takes the plural form. For example, “bus stops” (not “buses stop”), “mothers-in-law” (not “mother-in-laws”).
- Pronunciation: Stress often falls on the first word (e.g., “GREENhouse” vs. “green house”), though this isn’t universal.
- Spelling: There’s no strict rule for whether a compound noun is closed, open, or hyphenated—it’s often a matter of usage and evolution. Dictionaries can differ (e.g., “website” vs. “web site”), and preferences shift over time.
Important note
- It is important to remember that the way that compound nouns are written can change over time, and sometimes there are also differences between British and American English.
- The meaning of a compound noun is often different from the meanings of the individual words that make it up.
- The stress in a compound noun usually falls on the first word. Â
