Agonizing (adjective)
Causing physical or mental agony.
“It was an agonizing twenty-minute wait for the results.”
Agonizing (verb)
present participle of agonize
Agonizing (noun)
The act of one who agonizes.
Agonising (verb)
present participle of agonise
Wiktionary
Agonizing (adjective)
causing great physical or mental pain
“an agonizing death”
“there is an agonizing choice to make”
Oxford Dictionary