Brontotheres are extinct ungulates that existed during the Eocene epoch. Similar to rhinoceroses, they had a large body and a horn on their nose. The term "brontothere" can be replaced by several synonymous words like "Thunder Beast" due to their humongous size and thunderous movement. Another synonym would be "Titanotheres" which refers to their colossal size and immense strength. Some paleontologists also refer to them as the "Megacerops" due to their large size and ancient lineage. Additionally, the term "thunderer" can be used to describe the sound of their hooves hitting the ground. All these synonyms give a clearer image of the massive beast that once roamed the earth.