WordWeb Online

1. Causing or able to cause nausea
   "a sickening stench";
   - nauseating, nauseous, noisome, queasy, loathsome, offensive, vile, vomitous [US], loathful [archaic]

1. Cause aversion in; offend the moral sense of
   "The pornographic pictures sickened us";
   - disgust, revolt, nauseate, churn up
    
2. Get sick
   - come down
    
3. Upset and make nauseated
   "The mould on the food sickened the diners";
   - nauseate, turn one's stomach
    
4. Make sick or ill
   "This kind of food sickens me"

See also: gut-wrenching, unwholesome

Type of: decline, disgust, gross out, harm, repel, repulse, revolt, worsen