The concept of "the bush" has become iconic in Australia.[1] In reference to the landscape, "bush" refers to any sparsely-inhabited region, regardless of vegetation. "The bush" in this sense was something that was uniquely Australian[citation needed] and very different from the green European landscapes familiar to many new immigrants. The term "Outback" is also used, but usually in association with the more arid inland areas of Australia. "The Bush" also refers to any populated region outside of the major metropolitan areas, including mining and agricultural areas. Consequently, it is not unusual to have a mining town in the desert such as Port Hedland (Pop. 14,000) referred to as "the bush" within the media.[2]
https://en.wikipedia.org/wiki/The_bush

O termo bushranger refere-se a um tipo de bandido, muito bem adaptado à zona rural australiana (the bush), que assalta viajantes, moradias isoladas ou estabelecimentos comerciais de pequenas cidades.
http://www.abralic.org.br/eventos/cong2011/AnaisOnline/resum...

bush n as adj
US, Can, AU (rural, not sophisticated)
roça adj
http://www.wordreference.com/enpt/bush

bush
sertão (Austrália), terras selvagens, mato, campo
https://www.babylon-software.com/define/116/English-to-Portu...

Nota: sinceramente, não sei qual é o termo usado em pt-br.
Respondi com base no que encontrei nos dicionários e para lhe dar alguma ajuda.

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Note added at 1 hr (2019-03-17 22:52:01 GMT)
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Este texto é interessante; "bush" está quase como a nossa palavra "saudade", só os australianos é que entendem bem "the bush":

https://webcache.googleusercontent.com/search?q=cache:dFSrIv...

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Note added at 1 hr (2019-03-17 22:55:35 GMT)
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NOTA: em alguns textos em espanhol traduzem por "savana".