A day so big that it encompasses the activites and labour of an entire week. It is generally begun early in the morning followed by bad weather and lack of equipment and supplies.
Coady: We ran out of garbage bags.

Ed: And so the big day comes to an end
by foug June 13, 2003
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the day when someone gets married
She looked so happy on the big day.
by greatlexicographer September 13, 2013
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When you wake up and instantly feel big. During the day you can feel in the way and destructive and things often get in your way. The opposite can be a small day when you feel small and pathetic.
Brian woke up and hit his head on the door. Later on while eating his breakfast he noticed the spoon for his breakfast felt small, either the spoon was having small day of he was having a BIG DAY.
by Jakenyo July 22, 2016
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Australian music festival. A tradition, a rite of passage, a necessity to any Aussie music fan. Consistently attracts the biggest artists in the world.
Past acts have been Nirvana, Smashing Pumpkins, Hole, Korn, Metallica, The Strokes, The Prodigy, Blink 182, At The Drive-In, Foo Fighters, Queens of the Stone Age.
This year saw Beastie Boys, Slipknot, System of a Down, Chemical Brothers, The Hives, The Streets and more visit the best country in the world.
"Are you going to the Big Day Out this year?"
"Hell yes."
by me January 29, 2005
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The biggest, and best music festival in Australia. It tours Australia and New Zealand every year, and has some of the best music acts around. This year was the best ive been to, with The Killers, My Chemical Romance, Tool, Jet, Muse, Evermore, Eskimo Joe, The Presets, Lily Allen, Hot Chip and Sick Puppies.
The day runs from 10am till late, and features about 5 stages, so theres always someone good to listen to.
Plus, theres awesome rides and stuff if you get tired of the mosh environment!
Best day of the year!
I listened to The Killers from the top of the ferris wheel at Big day out '07. It was mad!
by Laurrr April 12, 2007
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a mocking term to refer to a female who sees fit to wear a tiara on her "big day out" such as at a bachelorette party, birthday, etc.

Hey look at you "big day out"

Hey big day out "where's the party?"
by dean_man December 23, 2008
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When the weather is just right and the humidity is at the right point to make one's balls appear extra large.
When I looked into the mirror this morning I knew it was a big ball day. Better call up my girl and make the porno now!
by TA3 July 22, 2009
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