unholy
Definitions
Contravening religious or moral principles; wicked or sinful.
Having an unnatural or sinister quality; devilish or demonic.
Extremely unpleasant, disagreeable, or unreasonable.
Examples
The abandoned mansion was filled with an unholy silence that made my skin crawl.
He made an unholy alliance with his political rivals to secure the vote.
The storm unleashed an unholy racket against the windows throughout the night.