Okay, this post is not about business writing. But over the next few days, plenty of people–perhaps you?–will be sending Mother's Day cards, notes, emails, tweets, and Facebook messages to mothers and motherly people.
I want to save you the trouble of wondering: Yes, Mother's Day does have an apostrophe–before the letter s. These renderings are correct:
- Happy Mother's Day!
- I want to wish you a happy Mother's Day! (There is no reason to capitalize happy although many people do.)
- On Mother's Day, I think of you.
Why the apostrophe? Because Mother's is a possessive form. The day of a mother is a mother's day, just as the house of your brother is your brother's house. The form is singular because each mother (singular) is celebrated.
We capitalize both Mother's and Day because Mother's Day is the proper name of a holiday.
Whether you are a mother or not, I wish you a happy May 11, Mother's Day.
P.S. Would you like to be more confident when it comes to punctuation? Take Punctuation for Professionals.