What are the other examples of irregular nouns?

A regular plural is a noun to which an -s or an -es is added to the end of the Word to form the plural.

An irregular noun is a noun that forms the plural in some other way. Examples of irregular plural nouns:

singular / plural

1. mouse / mice
2. company / companies
3. man / men
4. woman / women
5. child / children
6. person / people
7. goose / geese
8. ox / oxen
9. foot / feet
10. tooth / teeth
11. cactus / cacti
12. alumnus / alumni
13. medium / media
14. knife / knives
15. wife / wives
16. baby / babies
17. memory / memories
18. alumnus / alumni
19. bacterium / bacteria
20. pony / ponies