It's St. Patrick's Day, the day for celebrating the patron saint of the Emerald Isle, St. Patrick, and all things Irish. For the nearly 35 million Americans who identify as Irish — a group seven times as large as the actual population of Ireland — St. Patrick's Day is an opportunity to get in touch with their roots. They can start by getting the name of the holiday right. 

It's St. Paddy's Day, not St. Patty's Day. 

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The correct spelling of the holiday might seem a bit counterintuitive to North American English speakers. After all, "Patrick" is very clearly spelled with a "t," not a "d." But in Ireland, there is no doubt that it's "St. Paddy's." The people who run the Dublin airport's social media felt so strongly about the double "d" spelling that they decided to post a notice about it on the airport's Facebook page before St. Paddy's Day in 2014. 

"Please share this simple message with your friends and relations in the United States and Canada," the post said. "Using the power of your network, hopefully we can banish the scourge of St Patty once and for all."

The reason the Irish feel so strongly about the addition of the letter "d" into Patrick's name, seemingly out of nowhere, is that St. Patrick's name is spelled differently in Gaelic, the traditional tongue of Ireland. In Gaelic, Patrick is Pádraig, hence St. Paddy. The Irish use Patty as a nickname for Patricia, or, as the website paddynotpatty.com, points out, as a way to refer to a burger and "just not something you call a fella."

"There isn’t a sinner in Ireland that would refer to a Patrick as 'Patty.' It’s as simple as that," the site explains.