'wallaroo' originates from an Australian Aboriginal language (likely Dharug or another New South Wales language), specifically the word 'walaru' (recorded forms vary), where the root referred to a large native hopping marsupial.

'wallaroo' was adopted into early 19th-century Australian English from the Aboriginal word 'walaru' (or similar forms) and developed into the modern English form 'wallaroo'.

Initially the Aboriginal word referred broadly to a native hopping marsupial (a large macropod); over time in English it came to denote specifically the medium-sized macropods between wallabies and kangaroos.