Another dose of a drug consumed later after the first dose, but before the effects of the first wear off. Hence, boosting the effects of the drug back up to a high. Normally it is a lower dose, because not as much is required to bring the high back.
After I started coming down from my high, I needed a booster so I did another two lines of coke and felt much better.
by dinnerplates January 16, 2008

by pejman December 13, 2008

by Foreign.king July 9, 2016

by Ryan July 15, 2008

In Modern Warfare 2, a person or group of people who use Tactical Insertions to their advantage, go to a rarely-used place on a map, set the insertions, then continuously kill each other to get a free nuke or a bunch of free headshots. This is considered complete and utter cheating and is commonly rejected by professional players. MW2 pro "Sandy Ravage" has a series on YouTube called Booster Justice which is him killing boosters to no end.
by SOTE Czar July 27, 2010

by HighRoller_9 January 13, 2008

Online gaming: A person who sets up a secondary account which they use playing with a rival team. They help the rival team to lose, thus contributing to the progress of their primary team.
Blaze: WTF!? I just got killed by a guy on our side!
Silentsword: Kick him from the game! Get a life you fucking booster!
Booster: haha! You got owned! Your side sucks ass! You should join us!
Silentsword: Kick him from the game! Get a life you fucking booster!
Booster: haha! You got owned! Your side sucks ass! You should join us!
by Broadsword April 23, 2009
