sickening
adj.making you feel very upset, shocked, or physically ill. You use this to describe something that is extremely unpleasant or morally wrong.
adj.causing a feeling of physical nausea or intense moral revulsion. Often used predicatively after linking verbs like 'feel' or 'be'.
“The smell of the old food was sickening.”
“It was sickening to watch the powerful company take advantage of the poor families.”
“The witness provided a sickening account of the accident, detailing the events with a level of graphic precision that left the courtroom in stunned silence.”
Often follows linking verbs such as 'feel', 'look', or 'be'; can also modify nouns directly.
By surface analysis, sicken + -ing.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.