When most people think of Australia, one of the first words that comes to mind is outback. The outback is the vast (usually arid) interior and rural part of Australia. But outback as a word had its origins in the U.S.
The word was first used in the mid-1800s pretty literally: it was first used an adverb to refer to the space behind a house or a building, and especially the back yard of a house. The Aussies wittily borrowed this sense of out back to refer to the remote interior parts of their enormous continent:
Grass will be abundant out back.
— Wagga Wagga Advertiser, 17 Apr. 1869
By the end of the 19th century, the adverb had become the noun outback, and its generic "backyard" use dwindled as outback became more and more identified with the Australian interior.
Wait—isn't the vast and arid interior region of Australia actually called the bush? Not quite. The bush generally refers to areas of vegetated wilderness that are not as remote as the outback is. So while a person living in Sydney may spend their weekend hiking (or bushwalking) in the bush that lies just outside the city, they wouldn't take a weekend to go wander around the outback. (There is, however, an uptick in what's called "outback tourism," so even the outback is getting closer and closer to the city.)
The "Outback Steakhouse" chain restaurant is, incidentally, not Australian. It originated in Florida.