What is the German word for 'contamination'?

The correct term for 'contamination' in German is "Verunreinigung." This word specifically denotes the presence of unwanted substances which can pollute or adulterate a material or environment. In scientific and environmental contexts, "Verunreinigung" is often used to refer to various forms of contamination, such as in water, soil, or air, highlighting its relevance in discussions about pollution or health hazards.

The other options do not relate to 'contamination.' "Mischung" translates to 'mixture' and refers to a combination of different substances without the negative connotation of contamination. "Kupplung" means 'coupling,' typically referring to a mechanical joint or connection. Finally, "Hülse" signifies 'sleeve' or 'case,' which pertains to physical enclosures rather than contamination itself. This distinction underscores why "Verunreinigung" is the appropriate choice for the concept of contamination.