A "terrorist" intentionally targets innocent people in order to promote a political agenda.
Members of the Earth Liberation Front target only property, which invariably belongs to Earth-rapers with nothing innocent about them (HCN, 4/17/06: Eco-terrorism and the trial of the century). ELF has never killed or injured anyone. They are idealistic kids who claim that the courts and the legislators are in the pockets of the Earth-rapers, and so direct action is justified.
While rational and responsible criticisms can be made of their methods, referring to them as "terrorists" is neither rational nor responsible, and represents yet another effort by the Bush administration to demonize dissent.