When spelled with a capitol "S" and "D" (SeeD), it refers to a weirdo operation set into motion by Cid in the game Final Fantasy 8. You see, Cid married Matron Edea, a good sorceress, who was possessed by the consciousness of an evil sorceress named Ultimecia. Edea encouraged Cid to create SeeD as a method of killing her if Ultimecia ever took control of her body and started doing evil things.
I don't know if it's pronounced "CD" or "seed", but I don't really care.