Compound Nouns
Level B1 · Nouns & Quantity
A compound noun combines two or more words to name a single thing, and the words almost always keep a fixed order: the first word describes or limits the second, which is the main noun. a stone wall is a wall made of stone, not *a wall stone; a bus stop is a stop for buses, not *a stop bus — reversing the order changes or destroys the meaning.
How compound nouns are built and written:
- noun + noun is the most common pattern, with the first noun acting like an adjective and normally staying singular even when the meaning is plural: a shoe shop (a shop selling shoes, not shoes shop), a five-year-old (not five-years-old), a two-hour meeting (not two-hours meeting).
- Compound nouns are written three ways — as two separate words (car park), hyphenated (mother-in-law), or as one word (toothbrush) — and there's no fully reliable rule for which; newer or less common compounds tend to stay two words or hyphenated, while very familiar ones often merge into one.
- The main stress usually falls on the first word, which distinguishes a compound noun from a simple adjective + noun phrase: a 'greenhouse (a building for growing plants) vs a green 'house (a house painted green) — same words, different stress, different meaning.
- Other common patterns include verb + noun (a washing machine — a machine for washing), noun + verb+-ing (sunrise), and preposition-based compounds (a bystander, an onlooker).
The most common mistake is pluralizing the first noun in a noun+noun compound — a toys shop, three years old boy are wrong; the first noun normally stays singular: a toy shop, a three-year-old boy. A second mistake is reversing the word order, copying the pattern of another language — key car instead of car key, wall stone instead of stone wall; the describing word always comes first in English.
Look for two nouns placed together with no linking word (no of, no 's) where the first noun describes or limits the second and stays singular — if you can rephrase it as 'a [second noun] for/made of/related to [first noun]', you're looking at a compound noun, and the describing word goes first.