This is the 5182nd most frequent German word.
auer
"Auer" is not a standalone German word; it might refer to a proper noun like a surname or a part of a name.
Here, 'Dauer' is used as a noun meaning 'duration' to describe the length of an event.
Die Dauer des Spiels beträgt zwei Stunden.
The duration of the game is two hours.
In this sentence, 'Ausdauer' means 'endurance' and forms a compound noun with 'dauer' emphasizing persistence and stamina.
Er zeigte seine Ausdauer beim Marathon.
He demonstrated his endurance during the marathon.
The word 'dauerhaft' is an adjective derived from 'Dauer', meaning 'lasting' or 'durable' to describe the quality of a solution.