many types of nouns
in English. Compound nouns are a special type of noun made of two or more words. There are many compound nouns in English, so it is important to understand and learn them well.
To create the plural form of a compound noun, the plural ending is usually added to the noun. If compound words are formed with two nouns, the plural ending is added to the main noun.
lady-in-waiting => ladies-in-waiting
mother-in-law => mothers-in-law
outcome => outcomes
superpower => superpowers
football => footballs
overthrow => overthrows
assistant secretary of state => assistant secretaries of state
When a compound noun is formed with two nouns (printer cartridge; football), the second noun becomes plural. The first noun acts as an adjective because it describes the second noun. The second noun is the base noun.
printer cartridge => printer cartridges
peach tree => peach trees
wall clock => wall clocks
question mark => question marks
Some compound nouns do not have an obvious base word. You should use a dictionary to check the correct spelling of these compound nouns.