Question

What's the plural possessive form of mouse?

I know the singular possessive form is mouse's, but what is the plural possessive form?

Answer 1

The plural possessive noun is mice's .

Explanation:

The plural form of the noun mouse is mice.

Irregular plural nouns that don't end with an s form the possessive by adding an apostrophe s ('s), the same as making a singular noun possessive.

Answer 2

It would be better to finesse the problem.

Explanation:

Using "mice's" for the plural possessive doesn't sound exactly great.
The problem is that we don't usually add `'s` to plural words that end in `s`, so it sounds strange in the case of words that only end in an `s` SOUND

In general, the rule of modern punctuation is to write whatever matches the way you speak, and forget about those old rules.

If you SAY "My cat Sassafras's kittens are adorable," then that is what you should write, whether the word "Sassafras" ends in an s or not.

Saying "Sassafras' kittens are growing up" just doesn't sound right, so it should not be spelled that way.

But you would not say "The dresses's hems are too short," so you shouldn't spell it that way either.
"The dresses' hems are too short" sounds better.

The problem in the case of the mice is that saying "mice's" doesn't sound quite right, even though that is probably what you would actually say.
"The mice's burrows ran under the heap of oak leaves."
(I see that Microsoft's Spell Check doesn't like "mice's" either.)
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But in this case, there are two ways to avoid "mice's"

1) ~ The burrows dug by the mice ran under the heap of oak leaves.
This changes "mice's" to "of the mice" or "by the mice."

Here's another example:
The car's fender was dented. `rarr` The fender of the car was dented.
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2) ~ Mouse burrows ran under the heap of oak leaves.
This fix changes "mice's" into "mouse," an attributive noun modifying "burrows."