Here are the general rules for forming plural nouns in English:
1. Regular Plurals:
* Add -s to most nouns: cat -> cats, book -> books, chair -> chairs
* Add -es to nouns ending in -s, -x, -ch, -sh, or -z: bus -> buses, box -> boxes, church -> churches, brush -> brushes, buzz -> buzzes
* Add -ies to nouns ending in -y preceded by a consonant: baby -> babies, fly -> flies, story -> stories
* Change -y to -ies for nouns ending in -y preceded by a vowel: boy -> boys, toy -> toys, key -> keys
2. Irregular Plurals:
* Some nouns have irregular plural forms: man -> men, woman -> women, child -> children, tooth -> teeth, foot -> feet
* Some nouns remain the same in singular and plural: sheep -> sheep, deer -> deer, fish -> fish (can also be fishes)
3. Other Plural Forms:
* Compound nouns: Form the plural by adding -s to the main word: brother-in-law -> brothers-in-law, toothbrush -> toothbrushes
* Nouns ending in -f or -fe: Some change to -ves: knife -> knives, wife -> wives. Others add -s: roof -> roofs, chief -> chiefs
* Nouns ending in -o: Some add -es: hero -> heroes, potato -> potatoes. Others add -s: radio -> radios, photo -> photos
4. Noun Plurals in Special Cases:
* Proper nouns: For names of people, places, or things, the plural is usually formed by adding -s: Jones -> Joneses, the United States -> the United Stateses
* Uncountable nouns: These nouns don't typically have a plural form, as they represent something that cannot be counted: advice, information, furniture, water
It's important to remember that there are always exceptions to the rules, and some nouns can have multiple plural forms. Dictionaries can be a helpful resource for checking the correct plural form of a noun.