1. to make something dirty, polluted, or poisonous by adding a harmful or undesirable substance

Examples

• The factory contaminated the river with toxic chemicals.
• Bacteria can contaminate food if it’s not stored properly.
• The oil spill contaminated miles of coastline.
• Don’t let raw meat contaminate other foods in the refrigerator.
• The water supply was contaminated after the flood.
• Scientists worry that the nuclear accident could contaminate the soil for decades.