Now that the holiday cards are arriving, I’m seeing a lot of incorrect plurals, especially when it comes to family names. Apostrophes are rarely used when you are creating a plural noun. For example, when I am signing a card from our family, it should look like this:
CORRECT: From the Heims
INCORRECT: From the Heim’s
If you are pluralizing a name that ends in “s,” you should add an “es.”
When referring to dates or centuries:
CORRECT: 1990s, 1800s
INCORRECT: 1990’s, 1800’s
In rare cases, an apostrophe will be used for plurals for the sake of clarity.
Example: He received mostly A’s on his report card.
If we were to remove the apostrophe, it might be too confusing:
He received mostly As on his report card.
Finally, please be careful when using apostrophes to indicate possession.
Assuming that both of his parents live there, it should read:
CORRECT: He went to his parents’ house for Christmas.
If he has one brother:
He went to his brother’s house.
If he has two or more brothers living in the same house:
He went to his brothers’ house.
If he has two or more brothers living in different houses:
He went to his brothers’ houses.