infernal
Definitions
Relating to or characteristic of hell or the underworld.
Extremely troublesome, annoying, or irritating.
Fiendish or diabolical in nature.
Examples
The infernal heat of the desert sun made it nearly impossible to continue our hike.
I could not sleep all night because of the infernal racket coming from the construction site next door.
Synonyms
hellish diabolical fiendish damnable execrable abominable accursed