1. something that causes disgust, revulsion, or nausea
Usage: informal
2. something extremely disappointing or frustrating
Usage: informal; British

Examples

• The smell from the garbage was a real sickener.
• That violent scene in the movie was a complete sickener.
• Losing the match in the final minute was a sickener for the team.
• The corrupt politician’s behavior was a sickener to voters.
• Finding out the truth about his lies was a real sickener.
• The graphic images in the documentary were a sickener for many viewers.