One of several days, notably march 14th, 3/14, and the 22nd of July, representing a common fractional approximation 22/7. It's somewhat of a pointless holiday, but it's always fun to annoy the hell out of people by being able to recite digits of pi from memory.
I'm currently up to 15-ish digits of pi for pi day. 3.14159265358979323
by Jeff the Pirate March 14, 2007

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug
Top Definition
March 14th. A "holiday" celebrated by math geeks everywhere. Pi is approximately 3.14, and March the 14th is 3/14.
omg t3h pi day d00d, we are so 1337, pi roxxors t3h boxxors!
by aoiasimsd March 21, 2005

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug
Sorry, but the "true" math geeks are waiting for March 14, 2015 at 9:26 and 53 seconds AM to celebrate. Until then, we'll keep our differential equations and T-distributions to ourselves.
We who celebrate Pi day don't get out very much.
by Jeff42 March 15, 2007

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug
A "Math Day" held on March 14—after the first three digits of pi—when mean students with poor attitudes want to get even with their math teachers, by throwing pies at their face.
To celebrate or not to celebrate Pi Day? That's the question schools in crime-infected areas have been wrestling with for years, as teachers try not to let students-turned-"pi-rates" spoil the annual celebration, which aims to reveal the beauty and ubiquity of pi.
via giphy
by MathPlus March 07, 2017

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug
March 14th. A "holiday" celebrated by math geeks everywhere in USA and anywhere else the date is formatted MM/DD/YY. Pi is approximately 3.14, and March the 14th is 3/14 in America.
omg t3h pi day d00d, we are so 1337, pi roxxors t3h boxxors!

I know nothing about the outside world!
by Sam3453452 March 14, 2007

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug
In Europe, this day is celebrated on 22nd July. Pi used to be calculated in Ancient Greece as a fraction loosely calculated as 22/7.
Hey Joe, are you going to be having Pizza Pie or Apple Pie to celebrate this year's Pi Day?
by Jonathan FeBland March 14, 2007

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug
(March 14th)
A holiday celebrated by math teachers and geeks everywhere.
March 14th was the chosen day because pi = 3.14.
Since the next three numbers in the sequence are 159, at 1:59, everyone celebrating must say, "Happy Pi Day!"
And please, don't ask how I know.
J0HNNY: Oh my God! It's 1:59! Happy Pi Day!!
GEEK F0LL0WERS: Happy Pi Day!!!
J0CK: WTF?? Where's the pie?
H0HNNY && GEEK F0LL0WERS: Hahaha! Silly dumb kid!
by love x me <33333333333 March 15, 2007

The Urban Dictionary Mug

One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.

Buy the mug