1. a very small infectious agent that can only reproduce inside living cells and causes diseases
Usage: biology; medicine
2. a harmful computer program that can copy itself and damage or destroy data
Usage: computing
3. something harmful that spreads quickly from person to person
Usage: figurative

Examples

• The flu virus spreads easily during winter months.
• Scientists are studying how the virus attacks healthy cells.
• A computer virus infected thousands of computers worldwide.
• Make sure to install antivirus software to protect your files.
• The rumor spread like a virus through social media.
• Researchers developed a vaccine to prevent the virus.
• The virus corrupted all the data on his hard drive.