Jack is another name for a flag, usually a small flag used for signaling, but in the case of the Union Jack it symbolises the union of the three countries - England, Wales, Scotland
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petoria and seania
It symbolises the Great Britain links to Australia.
The Bahamas
Union Flag, or more casually the Union Jack
The Union Jack is the nickname of the UK flag.
UK, Australia, new zealand, Fiji, Samoa, new England
The United Kingdom, because it used to be part of the British Empire.
I'm not sure what you mean by 'special name', but the official name for the British flag is: Union Jack
The jack refers to the jackstay of a ship, on which the Union Jack would be displayed. Strictly speaking the flag should be called the Union Flag, but Union Jack is well known. Actually, the union jack is what the flag is called out at sea, but the union flag is what they call it on land.
The Union Jack is the United Kingdom's flag. It represents the four countries in the United Kingdom: Northern Ireland, Wales, Scotland and England. The flag has been used since the year 1801.