{f} make ill, infect with a sickness; fall ill, become infected with a sickness; nauseate, cause queasiness; become queasy, feel nauseous; cause disgust; be disgusted
get sick; "She fell sick last Friday, and now she is in the hospital" make sick or ill; "This kind of food sickens me" upset and make nauseated; "The smell of the foood turned the pregnant woman's stomach"; "The mold ont he food sickened the diners
You describe something as sickening when it gives you feelings of horror or disgust, or makes you feel sick in your stomach. This was a sickening attack on a pregnant and defenceless woman