• A noun can be used as a modifier to tell us a bit more about the noun it modifies. The modifier, in all cases, immediately precedes the noun. When a noun is used as a modifier, it is in its singular form, as indicated by the following examples:

Chicken/tomato/vegetable soup – We had a warm tomato soup as a starter.
Cargo/enemy/container/pirate ship – It took an hour for the dockers to load the cargo ship.
Language/business/village school – She's a language school teacher.
Gift/shoe shop – The gift shop also offers a large selection of leather goods at reasonable prices.
Police/sheep/family/farm dog – The police dog was sniffing round his heels.
Brick/concrete/stone/timber/wooden/airport/apartment/church/factory/farm/office building – We are renovating the old farm buildings after they were gutted by fire.
Hospital bed – He lay in the hospital bed, reading his book.
University laboratory – They are simulating the effects of weathering in the university laboratory.
Farm/country/council/mansion/tree/summer house – They rented a council house when they got married.

• When a noun used as a modifier is combined with a number expression, the noun is singular and a hyphen is used, as follow:

Half-timbered house – They build their own half-timbered house overlooking the river.
One-man – He does a one-man show in an open-air theatre. OR His one-man business is expanding fast.
Two-seater aircraft – The pilot overshot the runway and crashed his two-seater aircraft.
Three-day event – The three-day horse riding event will take place next week.
Four-bed house – They lived in a four-bedroom house in the suburbs.
Five-month contract – He has got a five-month contract to work on an offshore oil rig.
Six-year sentence – He will have to serve a six-year sentence for burglary.
Seven-girl band – She plays in a seven-girl rock band.
Eight-room mansion – The historic eight-room mansion stands in 60 acres of parkland.
100-year-old – The 100-year-old mansion stands in 60 acres of parkland.