How do you form the plural of compound noun?

Answer 1

The rules for making plural compound nouns are the same as the rules for making plural nouns. The ending of the word determines the form of the plural. For example:

• pole to poles; flagpole to flagpoles
• way to ways; doorway to doorways
• baby to babies; crybaby to crybabies
• box to boxes; breadbox to breadboxes
• knife to knifes; jackknife to jackknives

Answer 2

To form the plural of a compound noun, you generally add -s to the main noun in the compound if it's a regular plural form. For example, "book" in "bookstore" becomes "bookstores" in the plural. If the compound noun doesn't have a main noun, you can add -s to the end of the entire compound (e.g., "brother-in-law" becomes "brothers-in-law").