Definitions by Caofs

USDA 

United States Dumbledore´s Army.

Also DA
It´s an army. For Dumbledore.

If you read harry potter and the order of phoenix you will have more information.

Phil: Did you know she is in the USDA??

Joe: maybe that´s why she never gets on time to the dorm at night.
Phil: probably

USDA by Caofs January 2, 2011