The white rhinoceros or square-lipped rhinoceros (Ceratotherium simum) is one of the five species of rhinoceros that still exist. It has a wide mouth used for grazing and is the most social of all rhino species. The white rhino consists of two subspecies: the southern white rhino, with an estimated 17,460 wild-living animals at the end of 2007 (IUCN 2008), and the much rarer northern white rhino. The northern subspecies has very few remaining, all in captivity.

A popular theory of the origins of the name "white rhinoceros" is a mistranslation from Dutch to English. The English word "white" is said to have been derived by mistranslation of the Dutch word "wijd", which means "wide" in English. The word "wide" refers to the width of the rhinoceros' mouth. So early English-speaking settlers in South Africa misinterpreted the "wijd" for "white" and the rhino with the wide mouth ended up being called the white rhino and the other one, with the narrow pointed mouth, was called the Black Rhinoceros. Ironically, Dutch (and Afrikaans) later used a calque of the English word, and now also call it a white rhino. This suggests the origin of the word was before codification by Dutch writers. A review of Dutch and Afrikaans literature about the rhinoceros has failed to produce any evidence that the word wijd was ever used to describe the rhino outside of oral use. Other popular theories suggest the name comes from its wide appearance throughout Africa, its color due to wallowing in calcareous soil or bird droppings or because of the lighter colour of its horn. An alternative name for the white rhinoceros, more accurate but rarely used, is the square-lipped rhinoceros. The white rhinoceros' generic name, Ceratotherium, given by the zoologist John Edward Gray in 1868, is derived from the Greek terms keras (κερας) "horn" and therion (θηριον) "beast". Simum, is derived from the Greek term simus (σιμος), meaning "flat nosed".