What is the correct term for a harmful relationship between two organisms?

The correct term for a harmful relationship between two organisms is parasitism. In a parasitic relationship, one organism, known as the parasite, benefits at the expense of the other organism, called the host. This interaction can lead to various detrimental effects on the host, including disease, malnutrition, or even death, depending on the nature of the relationship and the specific organisms involved.

Mutualism refers to a relationship where both organisms benefit, creating a symbiotic connection that enhances the survival or reproduction of each party. Commensalism describes a situation where one organism benefits, and the other is neither helped nor harmed, indicating a neutral relationship. The term "asymbiotic" generally describes organisms that do not have a symbiotic relationship, but does not specifically imply harm. Thus, parasitism accurately characterizes a relationship where one organism inflicts harm on another.