Which term describes something that causes pain or suffering?

The term that describes something that causes pain or suffering is "harmful." This denotes an adverse effect, indicating that an action, substance, or situation negatively impacts individuals or the environment. In various contexts, harmful entities can lead to physical, emotional, or psychological distress.

In contrast, the terms "beneficial" and "advantageous" imply a positive outcome or effect that contributes to well-being or improvement, while "neutral" suggests a lack of significant positive or negative effect. Therefore, the core definition of "harmful" aligns perfectly with the notion of causing suffering or pain, making it the appropriate choice for this question.