What is the definition of 'nocuous'?

The term 'nocuous' is defined as harmful or poisonous, which is why the choice indicating this definition is the correct one. In medical and biological contexts, it often refers to substances or factors that can cause injury or adverse effects to living organisms. Understanding this term is important, especially in fields such as medicine, where recognizing harmful agents can have significant implications for patient safety and treatment. The other options pertain to entirely different concepts: one relates to anatomy (the back part of the head), another refers to reproductive status in women, and the last describes a specific field within dentistry. Each of these terms, while valid in their own contexts, does not align with the definition of nocuous.