What words can you change the vowel to make word plural?

This is a tricky one! There's no single word that can do this in English. Here's why:

* Pluralization rules are complex: English plurals are formed in different ways. Most often, we add "s" or "es" to the end of a word (cat -> cats, box -> boxes).

* Vowel changes are rare: While vowel changes *do* occur in some irregular plurals (e.g., man -> men, goose -> geese), they're not a common way to make a word plural.

So, there is no single word you can change the vowel in to make it plural.

Let me know if you'd like to explore other word-changing games or rules!