Form and use plurals of compound nouns

Key notes:

What are Compound Nouns?

👉 A compound noun is a noun made up of two or more words joined together to create a single idea.
Examples: toothbrush, mother-in-law, passer-by

Rules for Making Plurals of Compound Nouns

Add -s to the Main Word

➡ The important (main) word takes the plural form.

• Example: mother-in-law → mothers-in-law 👩‍👩‍👦
• Example: passer-by → passers-by 🚶

Add -s to the Last Word

➡ If the compound noun is one solid word or the last part is the main word.

• Example: toothbrush → toothbrushes 🪥
• Example: notebook → notebooks 📓

Add -s to Both Words (rare)

➡ Some compound nouns need plural on both words.

• Example: man-servant → men-servants 🧑‍🍳
• Example: woman-doctor → women-doctors 👩‍⚕️

Irregular Plurals

➡ Some change like regular irregular nouns inside the compound.

• Example: man-of-war → men-of-war ⚓
• Example: child-care worker → child-care workers 👶

Quick Tips

✔ Look for the main noun in the compound.
✔ Add plural (-s/-es) to it.
✔ If unsure, check in a dictionary 📖.

Examples

• brother-in-law → brothers-in-law 👬
• son-in-law → sons-in-law 👨‍👩‍👦
• lookout → lookouts 👀
• runner-up → runners-up 🏃‍♂️🥈
• maidservant → maidservants 🧹

Why Important?

✔ Helps you write grammatically correct ✍️
✔ Useful in speaking & writing 📢
✔ Makes your English more professional & clear 🌟