There are no reliable sources stating the didgeridoo's exact age. Archaeological studies of rock art in Northern Australia suggest that the people of the Kakadu region of the Northern Territory have been using the didgeridoo for less than 1,000 years, based on the dating of paintings on cave walls and shelters from this period. A clear rock painting in Ginga Wardelirrhmeng, on the northern edge of the Arnhem Land plateau, from the freshwater period (that had begun 1500 years ago) shows a didgeridoo player and two songmen participating in an Ubarr Ceremony.
A modern didgeridoo is usually cylindrical or conical, and can measure anywhere from 1 to 3 m (3 to 10 ft) long. Most are around 1.2 m (4 ft) long. Generally, the longer the instrument, the lower its pitch or key. However, flared instruments play a higher pitch than unflared instruments of the same length.
There are numerous names for the instrument among the Aboriginal peoples of northern Australia, none of which closely resemble the word "didgeridoo" (see below). Many didgeridoo enthusiasts and some scholars advocate reserving local names for traditional instruments, and this practice has been endorsed by some Aboriginal community organisations. However, in everyday conversation, bilingual Aboriginal people will often use the word "didgeridoo" interchangeably with the instrument's name in their own language.
"Didgeridoo" is considered to be an onomatopoetic word of Western invention. The earliest occurrences of the word in print include a 1908 edition of the Hamilton Spectator, a 1914 edition of The Northern Territory Times and Gazette, and a 1919 issue of Smith's Weekly where it was referred to as an "infernal didjerry" which "produced but one sound – (phonic) didjerry, didjerry, didjerry and so on ad infinitum".
A rival explanation, that didgeridoo is a corruption of the Irish language (Gaelic) phrase dúdaire dubh or dúidire dúth, is controversial. Dúdaire/dúidire is a noun that may mean, depending on the context, "trumpeter", "hummer", "crooner", "long-necked person", "puffer", "eavesdropper", or "chain smoker", while dubh means "black" and dúth means "native".