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1.
Term for one, espically in the MMFPS PlanetSide that shoots his own team, and thereby accumulates Greif points.
stay away from TyrTheAlpha, he is a greifer!

by Scythan August 17, 2003
 
2.
A person in the game Minecraft or Terraria that breaks player made structures using in game tools or TNT/dynamite on public servers.
That damn Greifer Blew up my house again !!!!
Better Ban Him
by Riloussa June 19, 2011
 
3.
(n.)

One who greifs
The 9th commandment: Thou shalt not hearken to the toungue of a greifer
by shooter June 03, 2004
 
4.
Greifer(s) 1: A person in World of Warcraft, who would proceed to spread a plauge that kills all low level players via infecting them with a debuff known as Corrupted Blood. aka "dickfuck".

(2) A person who is greiving over the loss of their significant other (lover,mother,pet,clown,seal/aquatic lifeform)
(1) *In WOWspeak* "ZOMFG greifer just debuffed IF, NUBZURZ GET OFF TEH PLANET OR I KICK YUR AZZ"

(2) "gee im sorry timmy, but i guess it was just your clowns time to go"
by WoWnub4life September 03, 2008