Slowly, more people seem to be getting the message that the correct way to abbreviate St. Patrick’s Day is St. Paddy’s Day, not St. Patty’s.
Every year, I remind my colleagues that if they feel that they absolutely must abbreviate St. Patrick’s Day, it’s correctly styled as St.  Paddy’s  Day.
“St. Patty’s Day,”  I tell them, would only be correct if we were honoring St. Patricia, not St. Patrick.
I wrote about this here at Patrick’s  Place back in 2014.
I’ve noticed over the years as I’ve made this annual reminder that more and more people, slowly, seem to be getting the message. I see more mentions of St. Paddy’s Day each year.
But just the other day, I received an email from O’Charley’s with the subject line, “Drink Green Beer & Celebrate St. Patty’s Day with us!”
“St. Patty’s Day?”
With a name like O’Charley’s, you’d assume they’d know how to style the short version of the holiday’s name. But O’Charley’s is a Southern-based restaurant, not an Irish one, so you have to cut them a little slack.
On the other hand, with a name like Patrick, I feel an obligation to point out that it should have invited people to celebrate “St. Paddy’s Day.”
Here’s why ‘St. Paddy’s Day’ is correct.
The short answer is simple: Paddy  is the abbreviation for  Patrick.  Patty  is the abbreviation for  Patricia.
The longer answer goes back to the history of St. Patrick and the Irish name itself. Patrick evolved from the Irish name Pádraig.
Even though the evolved name begins “PAT,”  not “PAD,”  the correct abbreviation, based on the proper nickname, would be Paddy. So, St. Patrick’s Day should be abbreviated as St. Paddy’s Day.
Patty, other than referring to a flattened cake of meat, as in a hamburger  patty or a chocolate covered candy, as in a Peppermint  Patty, is a nickname for Patricia.
For obvious reasons, we can’t go back and ask the patron saint for whom St. Patrick’s Day is named whether he minds having his name abbreviated.
Most Patricks I know would just as soon have people not abbreviate their name as “Paddy,”  and that might be a good reason never to use the abbreviation at all.
But if you have to, at least use the correct one!