look up any word, like blumpkin:
 
1.
A derisive and rather unkind name for a white person, often used in UK.
"you're seeing a greyback now is it?"

"you're such a greyback"
by Rumpole of the Bailey April 26, 2010
 
2.
Greybacks are dominant female gorillas.
Ex: The Greybacks are strong dominant females
by http://www.GorillaMic.com January 03, 2011