Herbivores were organisms that ate plants. On EarthWorld, the guidebook claimed that it meant they'd eat you if your name was "Herb". (PROSE: EarthWorld)
Herbivores had different teeth. They had incisors, which were used for cutting up food. Their molars were used for grinding up food and their pre-molars were used for chewing food. They ate vegtables. The sheep was a herbivore. (WC: Teeth and Eating)