The term was coined in the gold fields of Australia and came to typify the horrific experiences of Australian soldiers in battlefield trenches across the world.
As the nation paused to mark the 97th anniversary of the day Australian and New Zealand troops landed at Gallipoli in 1915, it has become an enduring word that encompasses the Anzac spirit, past and present.
At Melbourne's Shrine of Remembrance, in the cold and the rain, Afghanistan veteran Colonel Jason Blain said Anzac Day was about honouring the old Anzacs, but also the new.
"They're the ones with the responsibility to protect all that our nation holds precious," he said, of the 3000 personnel current serving overseas.
At services in every capital city, and dozens more in the smallest Australian communities, people turned out to remember and reflect.
In Adelaide, RSL spokesman Bill Denny told a dawn service all Australians must never forget the true horror of war.
"The overarching obligation we have ... is to truly recognise and accept the brutality, senselessness and futility of war," Mr Denny told about 8000 people gathered around the city's war memorial.
"War must never be glorified.
"We must commemorate the sacrifice and loss."
In Sydney, with no surviving WWI diggers to commemorate Anzac Day, it was the grandchildren and great grandchildren of the men and women who served in that conflict who joined thousands at the Cenotaph in Sydney's Martin Place for the dawn service.
A prayer for the troubled world opened the service and the assembled were asked to think of those in active service in Afghanistan, the Middle East, East Timor, the Solomons and Southern Sudan.
Guest speaker Rear Admiral Tim Barrett AM paid tribute to the courage, resilience and sacrifice of the original Anzacs.
More than 16,000 men landed on Anzac Cove on the first day of the landing, 2000 of whom lost their lives.
"It was on this day that Australia's identity was forged," Admiral Barrett said.
"It is the Anzac spirit that shows us not who we intrinsically are, but who we want to be."
In Brisbane, 10-year-old Hayley Pitt understood why she was woken up at 2am to travel into the city with her family.
"Because they died for our free country," she said as she stood in Anzac Square waiting for the sun to rise and the bugle to ring out.
Her great-grandfather served in Papua New Guinea in World War II and it was for him that her entire family made the trip from Redland Bay for the ceremony, Hayley's grandfather Harry Jarman said.
"I think it's important to remember what soldiers went through during the war," Mr Jarman told AAP.
Queensland Governor Penelope Wensley told those attending that the identities of Australia and New Zealand were forged on the beaches of Gallipoli in 1915.
"... it was the defining moment in the life of a new nation, giving rise to something that has defined Australia and Australians, New Zealand and New Zealanders ever since.
"That unique, irrepressible, admirable set of qualities that together form the Anzac spirit."
In Canberra, at the Australian War Memorial, Salvation Army Lieutenant Colonel Philip Cairns spoke of the sobering thought that occurs to every digger.
"Would they be prepared to die for their country? All too often in our history the answer to this question has had to be yes," he said.
"We can only stand in admiration this morning and say thank you."
The words of a schoolboy at Tasmania's dawn service summed up the thoughts of millions on Anzac Day.
"Anzac Day means sacrifices, carnage and the sweet aroma of rosemary floating above the trenches and corpses of Gallipoli," said primary school student Liam O'Donnell-Adams.
Delivering the student's address beneath Hobart's Cenotaph, he put a new spin on the mateship that so defines Australia's day of remembrance.
Across the Tasman, thousands gathered at the Wellington Cenotaph for a dawn service to honour the Anzac legacy, unaware of a non-specific bomb threat at the commemorations.
For William Antrobus, 9, it was a special occasion - both his birthday, and his first Anzac service.
With brother Mitchell, 7, and father Sean, William wore the medals of his great-grandfather, Ted Thompson, who served in North Africa in World War II.
"It's special to me since people from both sides of my family have been in the war," William told AAP.
Prime Minister Julia Gillard and Governor-General Quentin Bryce will attend a service in Gallipoli itself, where the Anzac legend began almost a century ago.
They will be joined by the thousands of young Australians, including Victoria Cross recipient Ben Roberts-Smith, who travel to Turkey each year in what has become a national rite of passage.
Veterans Affairs Minister Warren Snowdon will observe Anzac Day on the Western Front, at the major Australian memorial at the French town of Villers-Bretonneux.
Defence Minister Stephen Smith will attend the Anzac Day dawn service at Port Moresby's Bomana War Cemetery, marking the 70th anniversary of the fighting on the Kokoda track.
From there he will head to the Solomons to visit the 84 soldiers who form the Australian component of the peace-keeping mission there.