This is the 1594th most frequent German word.
nieder
"Low" or "down."
Here, 'nieder' is used in the sense of moving down or settling, implying motion towards a lower position.
Er ließ sich neben dem Baum nieder.
He settled down next to the tree.
In this usage, 'nieder' conveys the concept of opposition or rejecting something, often used in slogans or exclamations.
Die Soldaten riefen laut und nieder mit der Tyrannei.
The soldiers shouted loudly, 'Down with tyranny!'
In this example, 'nieder' is integrated with the verb to indicate the action of sitting down or lowering oneself to the sitting position.