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1.
A term used to describe distribution or release of digital media (such as software, video or music) before it is sold in stores or before it hits the street. Zero-day releases may be pirated or stolen and may break the law, but not all zero-day releases are obtained illegally.
To own a copy of the next version of Windows two weeks before its official release date.
by Pascal September 21, 2003
23 5
 
2.
ZERO DAY was the code-word that two students used to describe the assault they planned for over a year, and which they finally executed on May 1st, 2001.

On that warm and beautiful spring day, Andre Kriegman and Calvin Gabriel, two students of Iroquois High School, walked onto to their campus with three semiautomatic weapons, a shotgun, a revolver, at least twenty explosive devices and several knives.

ZERO DAY, the movie, brings us into the world of best friends Andre and Calvin.

Self-named the "Army of Two" they used video cameras to record everything relevant to their final "mission." Their video diaries provide a window into their chillingly ordinary lives, and as we get to know them we become seduced by their intelligence, their humor, their directness, the inward and outward expressions of their adolescence, and their terrible single-mindedness.
Andre: Zero Day movie bro.. youtube.com/watch?v=pgRDWjafLm4
Calvin: O_O wow, we're brutal.
by Gregz0rzz December 11, 2006
27 12
 
3.
warez'ed software, usually, that's distributed really quickly, perhaps even on the official software release date or before.
Come into this chan for hot zero-day xdcc bots!
by schmiddy September 22, 2003
3 2
 
4.
No time left to do whatever you had planned to do, the day you die, or the day that your life will metaphorically end (be put in jail for life)
He hadnt come up with the money, it was zero-day.
by james "the snake" ricardo September 19, 2003
1 5
 
5.
usually day of release for music or games on the internet relating to the pirate groups that release it on the internet
warez, mp3z, appzz, gamez
by hk September 21, 2003
1 7
 
6.
post whore.
zeroday is a friggin post whore.
by beavis October 02, 2003
3 10