Old School or Oldschool.
That trick was insane OS!

That suit is so OS! (Colorfull suit from the 80's)
by Vegard & Lars April 28, 2006
This is an abbreviation used exclusively for games in the Halo series. It stands for OverShield.
p1: wtf? how didn't you die?

p2: I picked up an OS
by Drüd August 31, 2008
Slang word for a power up in the popular game Halo 2 means Overshield. Gives you 2 extra layers of shield
"Pick up the OS you wont die!"
by Mex4life1992 November 11, 2006
"Oh Shit" Sometimes used in first person shooting games.

See Also: oh shit omg
Os! I got shot in the face!
by Iamgod00021 May 20, 2006
Operating System. Windows is the only one worth your money, with the downside of constant errors (and the blue screen trauma).
by Bastardized Bottomburp May 03, 2003
A nicer way of calling someone a 'Hoe'
Ayye manggg, you see those O's over there? I heard they give good head!
by doodmamas<3 December 09, 2009
acronym for operating system. the best one is teh Mac OS, followed by Unix, then Linux and finally Windows (hands down the worst OS on earth)
Apple and Microsoft are competing against each other to get more people to use their OSes
by teh_applegoddess July 07, 2003

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