A compound noun is a noun made of two or more words that work together as a single unit.
Three Forms
| Form | Rule | Examples | | -------------- | ------------------------- | -------------------------------------------------- | | Closed | Written as one word | toothbrush, bedroom, haircut, football, notebook | | Open | Written as separate words | ice cream, post office, swimming pool, bus stop | | Hyphenated | Joined with a hyphen | mother-in-law, six-pack, check-in, well-being |
How Compound Nouns Are Formed
| Combination | Examples | | ------------------ | ------------------------------------------------- | | Noun + Noun | bedroom, toothpaste, bookshelf | | Adjective + Noun | blackboard, greenhouse, full moon | | Verb + Noun | washing machine, swimming pool, driving licence | | Noun + Verb | sunrise, rainfall, haircut | | Preposition + Noun | underworld, overtime, afternoon | | Verb + Preposition | breakdown, checkout, makeup |
Plural of Compound Nouns
- For closed compounds, add the plural at the end: toothbrushes, footballs
- For open compounds, pluralise the main noun: post offices, swimming pools
- For hyphenated compounds, pluralise the main noun: mothers-in-law, passers-by
Common Mistakes
- ❌ I need a tooth paste. → ✅ I need toothpaste.
- ❌ She has two mother-in-laws. → ✅ She has two mothers-in-law.
- ❌ Let's play foot ball. → ✅ Let's play football.