This is the 16013th most frequent Russian word.
пугающему
"Пугающему" means "to something/someone frightening" in English.
Here, 'пугающему' is an adjectival form modifying 'миру,' describing it as 'terrifying' or 'frightening' in nature.
Книга была посвящена пугающему миру тайн.
The book was dedicated to the terrifying world of mysteries.
In this sentence, 'пугающему' refers to 'звуку,' characterizing it as 'frightening' or 'causing fear.'
Мы подошли ближе к пугающему звуку, исходящему из темноты.
We approached the terrifying sound coming from the darkness.
Here, 'пугающему' is used to describe 'клоуну,' indicating that the clown in question is perceived as 'terrifying.'