How do you make words ending in ful into plural?

Words ending in "ful" follow the standard English plural rule for nouns: add "s" to the end.

Here are some examples:

* useful -> usefuls

* beautiful -> beautifuls

* thankful -> thankfuls

* powerful -> powerfuls

However, it's important to note that using the plural form of words ending in "ful" is uncommon and often considered grammatically incorrect.

Here's why:

* "Ful" is a suffix, not a standalone noun: Words ending in "ful" are adjectives, not nouns.

* We usually use the plural form of the noun that the adjective modifies: For example, instead of "beautifuls," we would say "beautiful flowers" or "beautiful women."

So, it's generally better to use the plural form of the noun the adjective describes.