At the beginning of the Philosopher's Stonethe Philosopher's Stone, the description of Dumbledore is as follows:
He was tall, thin and very old, judging by the silver of his hair and beard, which were both long enough to tuck into his belt. He was wearing long robes, a purple cloak which swept the ground and high-heeled, buckled boots. His blue eyes were light, bright and sparkling behind half-moon spectacles and his nose was very long and crooked, as though it had been broken at least twice.
We know that Dumbledore had his nose broken at the funeral by Aberforth.
Was his nose broken another time, or was this just a particularly severe break?