Australian English is the de facto official language of Australia and, although it has no official status in the Constitution, is the first language of the majority of the 24 million people living there.
Australian English began to diverge from British English after the founding of the Colony of New South Wales in 1788. By 1820 it was already recognised as being a different type of English. As the early settlers from many regions of the British Isles intermingled in the new colonies there, the various accents and dialects quickly gave rise to the Australian English we know today. The earliest speakers were the children of the first colonists.
Certain elements of Aboriginal languages have become part of Australian English, mostly for the names of places, plants and animals. Some examples that have come into use globally are kangaroo, boomerang, budgerigar and wallaby. The name of the capital Canberra means 'meeting place' in the local aboriginal language. Other aboriginal words used only in Australian English are yakka, meaning work, and bung, meaning dead, broken or useless.
Unique words and idioms
Australian English has many words and idioms that are unique. The Macquarie Dictionary is widely regarded as the definitive dictionary of these. Well-known examples include outback (a remote area), creek (a small river), paddock (a field), g'day (a general greeting) and fair dinkum (true). Australian English is also known for using diminutives (shortening words and expressions). Common examples include arvo (afternoon), barbie (barbecue), Aussie (Australian) and pressie (present).
Spelling and style
Australian spelling is closer to British than American spelling. For example, it retains the 'u' in words such as colour, labour and favour. Also, 're' is preferred over 'er' in words such as theatre and centre. There are some individual words which the Macquarie Dictionary lists as being different to the British spelling. These include program, inquire, analog, livable and verandah.
Please feel free to add your own examples of Australian English to this post!