This is the 15251st most frequent German word.
unaufhörlich
Unceasing; incessant; continuous.
Here, 'unaufhörlich' is used to describe the constant and uninterrupted nature of the rain.
Die unaufhörliche Regenfall hat den Boden durchnässt.
The incessant rain has soaked the ground.
In this context, 'unaufhörlich' emphasizes the non-stop manner of his speaking.
Er sprach unaufhörlich über sein neues Projekt.
He spoke incessantly about his new project.
The word 'unaufhörlich' describes the continuous and persistent buzzing sound.